D-MANNITOL DERIVATIVES AS HIV ASPARTYL PROTEASE INHIBITORS

Abstract: A D-mannitol derivative selected from the group consisting of a compound of formula (I) pharmaceutically acceptable derivatives thereof and where applicable or appropriate pharmaceutically acceptable salts thereof, wherein R1, R2, R3 and R4 are the same or different and may, for example, each independently be selected from among alkyl and aryl (i.e. aromatic including aromatic like) groups. The D-mannitol derivatives may be used as HIV aspartyl protease inhibitors.

Description: D-MANNITOL DERIVATIVES AS HIV ASPARTYL PROTEASE INHIBITORS. TECHNICAL FIELD OF THE INVENTION The present invention relates to a compounds with aspartyl protease inhibitory properties. This invention in particular relates to D-mannitol derivatives with HIV aspartyl protease inhibitory properties that have been characterized by specific structural and physicochemical features. In addition, this invention also relates to pharmaceutical compositions exploiting these compounds. The compounds including the pharmaceutical compositions of this invention are able to inhibit the activity of HIV aspartyl protease. Accordingly, this inhibitory property may be advantageously used to provide compounds with antiviral properties against HIV viruses, including the HIV-1 and HIV-2 viruses. BACKGROUND OF THE INVENTION The HIV (human immunodeficiency virus) retrovirus is the causative agent for AIDS (acquired immunodeficiency syndrome). Thus the HIV-1 retrovirus primarily uses the CD4 receptor (a 58 kDa transmembrane protein) to gain entry into cells, through high-affmity interactions between the viral envelope glycoprotein (gp 120) and a specific region of the CD4 molecule found in T- lymphocytes and CD4 (+) T-helper cells (Lasky L.A. et al, Cell vol. 50, p. 975-985 (1987)). HIV infection is characterized by a period immediately following infection called "asymptomatic" which is devoid of clinical manifestations in the patient. Progressive HIV-induced destruction of the immune system then leads to increased susceptibility to opportunistic infections, which eventually produces a syndrom called AIDS-related complex (ARC) characterized by symptoms such as persistent generalized lymphadenopathy, fever, weight loss, followed itself by full blown AIDS. After entry of the retrovirus into a cell, viral RNA is converted into DNA, which is then integrated into the host cell DNA. The reverse transcriptase encoded by the virus genome catalyzes the first of these reactions (Haseltine W. A. FASEB J. Vol. 5 2349 - 2360 (1991)). At least three functions have been attributed to the reverse transcriptase: RNA-dependent DNA polymerase activity which catalyzes the synthesis of the minus strand DNA from viral RNA, ribonuclease H (RNase H) activity which cleaves the RNA template from RNA-DNA hybrids and DNA-dependent DNA polymerase activity which catalyzes the synthesis of a second DNA strand from the minus strand DNA template (Goff S. P. J. Acq. Imm. Defic. Syndr., vol. 3 p. 817 - 831 ( 1990)). The double stranded DNA produced by reverse transcriptase, now called pro virus, is then able to be inserted into host genomic DNA. At the end of reverse transcription, the viral genome now in the form of DNA is integrated into host genomic DNA and serve as a template for viral gene expression by the host transcription system, which leads eventually to virus replication (Sakai, H al.,J. Virol. Vol. 67, p. 1169-1174 (1993)). The preintegration complex consists of integrase, reverse transcriptase, pi 7 and proviral DNA (Bukrinsky et al, Proc. Nat. Acad. Sci. USA vol. 89, p. 6580 - 6584 (1992)). The phosphorylated pi 7 protein plays a key role in targeting the preintegration complex into the nucleus of host cell (Gallay et al., Cell, vol. 80, p. 379 - 388 (1995)). The primary RNA transcripts made from the provirus are synthesized by the host cell RNA polymerase II which is modulated by two virus-encoded proteins called Tat and Rev. The viral proteins are formed as polyproteins. Post-translational modifications of viral polyproteins include processing and glycosylation of Env (envelope) proteins, and myristylation of the N-terminal residue of the pi 7 protein in the Gag and Gag-Pol polyproteins. The latter two precursors correspond to structural proteins and viral enzymes. The viral protease is involved in processing polyproteins Gag and Gag-Pol into mature proteins, a step essential for virus infectivity. A number of synthetic antiviral agents have been designed to block various stages in the replication cycle of HIV. These agents include compounds which interfere with viral binding to CD4 T-lymphocytes (for example, soluble CD4), compounds which block viral reverse transcriptase (for example, didanosine and zidovudine (AZT)), budding of virion from the cell (interferon), or the viral protease (for example Ritonavir and Indinavir). Some of these agents proved ineffective in clinical tests. Others, targeting primarily early stages of viral replication, have no effect on the production of infectious virions in chronically infected cells. Furthermore, administration of many of these agents in effective therapeutic doses has led to cell-toxicity and unwanted side effects, such as anemia, neurotoxicity and bone marrow suppression. Anti-protease compounds represent the most recent drugs developed to block HIV replication. These compounds inhibit the formation of infectious virions by interfering with the processing of viral polyprotein precursors. Thus, the antiviral potential of HIV protease inhibition has been demonstrated using peptidic inhibitors. Such peptidic compounds, however, are typically large and complex molecules that tend to exhibit poor bioavailability and are not generally consistent with oral administration. Accordingly, the need exists for compounds that can effectively inhibit the action of viral proteases, for use as agents for preventing and treating chronic and acute viral infections, such as HIV. SUMMARY OF THE INVENTION The present invention relates to mannitol derivatives, including their pharmaceutically acceptable derivatives. These compounds have an affinity for aspartyl proteases, in particular, HIV aspartyl protease. Therefore, these compounds may be useful as inhibitors of such proteases. These compounds may be used alone or in combination with other therapeutic or prophylactic agents, such as antivirals, antibiotics, immunomodulators or vaccines, for the treatment or prophylaxis of viral infection. Compounds of this invention are capable of inhibiting HIV viral replication in human CD4+ T-cells, by inhibiting the ability of HIV aspartyl proteases to catalyze the hydrolysis of peptide bonds. These novel compounds can thus serve to reduce the productior of from acutely and chronically infected cells, and can inhibit the initial or further infection of host cells. Accordingly, these compounds may be useful as therapeutic and prophylactic agents to treat or prevent infection by HIV-1 and related viruses, which may result in asymptomatic HIV-1 infection, AIDS-related complex (ARC), acquired immunodeficiency syndrome (AIDS), AIDS-related dementia, or similar diseases of the immune system. Acccordingly, the present invention relates to D-mannitol derivatives that may be used as aspartyl protease inhibitors, and particularly, HIV aspartyl protease inhibitors. Accordingly, the present invention provides a D-mannitol derivative selected from the group consisting of a compound of formula 1 pharmaceutically acceptable derivatives thereof and where applicable or appropriate pharmaceutically acceptable salts thereof (e.g. when a compound of formula 1 comprises a carboxylic acid group pharmaceutically acceptable salts thereof and when a compound of formula 1 comprises an amino group pharmaceutically acceptable ammonium salts thereof), wherein R,, R 2 , R 3 and R 4 are the same or different and may each independently be selected from among alkyl and aryl (i.e. aromatic including aromatic like) groups. The aromatic (or aromatic like) group may be an aromatic hydrocarbon group, an aromatic heterocyclic group, an allyl group, a cyclopropylmethyl group, a alkylthiothioxo group, an aroyl group and the like. In addition, this invention provides pharmaceutical compositions in which the D-manhitol derivatives (e.g. derived from D-mannitol) may be used to inhibit aspartyl proteases, including HIV aspartyl proteases, thus providing protection against HIV infection. The term "heterocycle" "heterocyclic group" and the like refer to a stable 5 - 7 membered monocycle or bicyclic heterocycle, which may be optionally benzofused or heterocyclofused. Each heterocycle consists of carbon atoms and from one to four heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. As used herein, the terms "nitrogen and sulfur heteroatoms" include any oxidized form of nitrogen and sulfur, and the quaternized form of any basic nitrogen. The heterocyclic ring may be attached by any heteroatom or carbon atom of the cycle, which may for example give rise to benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrroldinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl. The substituents R,, R 2 , R 3 and R 4 for the compound of formula 1 above may, for example, be selected from the group consisting of C, to C 5 alkyl (e.g. methyl), -(C, to C 5 alkylene) m - Ar -(C=O)-(C, to C 5 alkylene) m - Ar -(C=S)-(C, to C 5 alkylene) m - Ar -(C=O)-O-CH 2 - Ar -(C=S)-S-CH 2 - Ar and -(C=S)-S-CH 3 wherein m denotes 0 or 1 and Ar is an unsubstituted aromatic (or aromatic like) group or a mono or polysubstituted aromatic (or aromatic like) group. The group Ar may for example be an unsubstituted or substituted benzyl group (i.e. m = 1, alkylene = methylene and Ar = unsubstituted or substituted phenyl). The aromatic (or aromatic like) group may, for example, be substituted by one or more members of the group consisting of halogen atoms, amino groups, amino acid groups, carboxylic acid groups, alkylthio groups, cyano groups, hydroxyl. alkoxy groups, carbonyl groups, etc. The aromatic (or aromatic like) group may, for example, be 2-thienylmethyl, 2-.3-,4-pyridylmethyl, 2-naphthylmethyl, allyl, cyclopropylmethyl, and the like. More particularly the group Ar may be selected from the group consisting of allyl, vinyl, styryl, cyclopropyl, naphthyl, aromatic heterocyclic groups (such as pyridyl and thienyl), unsubstituted phenyl and phenyl which is substituted by one or more members of the group consisting of -CI, -F, -Br, -I, -CN, -A-CN, -CF 3 , -A-CF 3 , -NO 2 , R 5 -CO, R 5 -CO-A-, - OCH 2 C 6 H 5 , -A-S(O) n -R 5 , straight or branched C, to C 6 alkyl, -A-OR 5 , -OR 5 , -NI^ R 7 , -A- NR,R 7 , -COOR 8 , -A-COOR 8 . -A-NHCOR 8 , -NHCOOR 8 and -A-NHCOOR 8 , wherein n denotes 0, 1 or 2, A represents an alkylene group having from 1 to 5 carbon atoms (e.g. methylene), R 5 is selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C π methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl. oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl. tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl; Rg and R 7 are each and independently selected from the group consisting of H and straight or branched C, to C 6 alkyl. straight or branched C 2 to C 6 alkenyl, C 4 to C u methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl or R 6 and R 7 together with the nitiOgen atom to which they are bonded represent a (saturated or unsaturated) heterocyclic group of formula wherein Ya and Za each independently denotes a hydrocarbon chain comprising 1 to 3 carbon atoms, Xa denotes O and n' denotes 0 or 1, provided that when n' denotes 1 Ya and Za cannot both comprise 3 carbon atoms at the same time and that when n' denotes 0 Ya and Za are bonded directly together (e.g. the heterocyclic may be pyridyl, morpholinyl and the like) and; R 8 is selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C u methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, moipholinecarbodithioyl and sulfolanyl. The present invention, in particular, provides a compound of formula la: pharmaceutically acceptable derivatives thereof and where applicable or appropriate pharmaceutically acceptable salts thereof (e.g. when a compound of formula la comprises a carboxylic acid group pharmaceutically acceptable salts thereof and when a compound of formula la comprises an amino group pharmaceutically acceptable ammonium salts thereof), wherein R„ R 2 , R 3 and R 4 are each independently (i.e. same or different) selected from the group consisting of unsubstituted benzyl and benzyl which is substituted by one or more members of the group consisting of -CI, -F, -Br, -I, -CN, -A-CN, -CF 3 , -A-CF 3 , -NO,, R 5 -CO, R 5 -CO-A-, -OCH 2 C 6 H s , -A-S(O) n -R 5 , straight or branched C, to C 6 alkyl, -A-OR 5 , -OR 5 , -NR« R 7 , -A-NI^R,, -COOR 8 , -A-COOR 8 , -A-NHCOR 8 , -NHCOOR 8 and -A-NHCOOR 8 , wherein n denotes 0, 1 or 2, A represents an alkylene group having from 1 to 5 carbon atoms, R 5 is selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C π methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl; Rg and R 7 are each and independently selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C u methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl or R 6 and R 7 together with the nitrogen atom to which they are bonded represent a (saturated or unsaturated) heterocyclic group of formula wherein Ya and Za each independently denotes a normal (i.e. unbranched) hydrocarbon chain comprising 1 to 3 carbon atoms, Xa denotes O and n' denotes 0 or 1, provided that when n' denotes 1 Ya and Za cannot both comprise 3 carbon atoms at the same time and that when n' denotes 0 Ya and Za are bonded directly together (e.g. the heterocyclic may be pyridyl, morpholinyl and the like), and; R^ is selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C π methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl. The present invention in particualr provides a compound of formula la wherein R, and R 4 are the same and each denote an unsubstituted benzyl, where R 2 and R 3 are the same and each denote a benzyl group of formula wherein Rg is selected from the group consisting of -CI, -F, -Br, -CN, -CF 3 , -NO,, -CHO, - OCH,C 6 H 5 , -CH 3 , -NH 2 , -OH, -COOCH 3 , -COOH, -CH 2 NH 2 , -CONH 2 , -NH-tert- butyloxycarbonyl and -NHCOOR 10 wherein R 10 is -H or tert-butyl The present invention also in particular provides a compound of formula la wherein R, and R 3 are the same and each denote an unsubstituted benzyl, where R, and R 4 are the same and each denote a benzyl group of formula wherein R n is selected from the group consisting of -CI, -F, -Br, -CN, -CF 3 , -NO 2 , -CH 2 OH, CH 3 , -NH,, -COOR 12 , -COOH wherein R 12 is methyl or Λrø-butyl. The present invention further provides a compound of formula la wherein R, and R 4 are the same and each denote a benzyl group of formula wherein R 14 is selected from the group consisting of -F, -CN, CF 3 , -OH, -CH 3 and OCH 2 C 6 H 5 and wherein R, and R 3 are the same and each denote a benzyl group of formula wherein R 15 is selected from the group consisting of -F, -CN, -CF 3 , -OH and CH The present invention in addition particularly provides a compound of formula la wherein R R,, R 3 and R 4 are each independently (i e. same or different) selected from the group consisting of unsubstituted benzyl and benzyl which is substituted by one or more members of the group consisting of F and -OH, and provided that at least one of R,, R 2 , R 3 and R 4 is benzyl which is substituted by one or more members of the group consisting of F and -OH In accordance with the present invention there is also provided a compound of formula la wherein R, and R 3 are the same and each represents a benzyl group of formula and wherein R, and R 4 are the same or different and each represents a benzyl group of formula wherein n is 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH In accordance with the present invention there is further provided a compound of formula la wherein R, and R 3 are the same and each represents a benzyl group of formula wherein R, is an unsubstituted benzyl group and wherein R 4 represents a benzyl group of formula wherein n is 1 or 2 and Z is selected from the group consisting of -OH, F^ -OCH 3 and ?CH 3 . In accordance with the present invention there is additionally provided a compound of formula la wherein R, and R 4 are the same and each represents a benzyl group of formula and wherein R, and R 3 are the same or different and each represents a benzyl group of formula wherein n is 0, 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH 3 . In accordance with the present invention there is further provided a compound of formula 1 a wherein R, represents a benzyl group of formula wherein R, represents a benzyl group of formula wherein R 3 represents an unsubstituted benzyl group and wherein R 4 represents a benzyl group of formula wherein n is 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH 3 . Combinations of substituents and variables envisioned by this invention are only those that result in the formation of stable compounds. The term "stable", as used herein, refers to compounds which possess stability sufficient to allow manufacture and administration to a mammal by methods known in the art. Typically, such compounds are stable at a temperature of 40°C or less, in the absence of moisture or other chemically reactive conditions, for at least a week. The compounds of formula 1 (or formula la) of this invention contain one or more asymmetric carbon atoms and thus may occur as racemates and racemic mixtures, single enantiomer, diastereomeric mixtures and individual diastereoisomers. All such isomeric forms of these compounds are expressly included in the present invention. Each stereogenic carbon may be of the R or S configuration. The terms "HIV protease" and "HIV aspartyl protease" are used interchangeably and refer to the aspartyl protease encoded by the human immunodeficiency virus type 1 or 2. In a preferred embodiment of this invention, these terms refer to the human immunodeficiency virusiype 1 aspartyl protease. The term "pharmaceutically effective amount" refers to an amount effective in treating HIV infection in a patient. The term "prophylactically effective amount " refers to an amount effective in preventing HIV infection in a patient. As used herein, the term "patient" refers to a mammal, including a human. The term "pharmaceutically acceptable carrier or adjuvant" and "physiologically acceptable vehicle" refer to a non-toxic carrier or adjuvant that may be administered to a patient, together with a compound of this invention, and which does not destroy the pharmacological activity thereof. As used herein, the compounds of formula 1 (or formual la) of this invention, are to be to be understood as being defined to include pharmaceutically acceptable derivatives thereof. Thus a "pharmaceutically acceptable derivative" means any pharmaceutically acceptable salt, ester, or salt of such ester, of a compound of formula 1 (or formula la) of this invention as well as any other compound which, upon administration to a recipient, is capable of providing (directly or indirectly) a compound of this invention or an antivirally active metabolite or residue thereof. Salts derived from appropriate bases include alkali metal (e.g., sodium, potassium, cesium, etc.). alkaline earth metal (e.g., magnesium), ammonium and N - (C,. 4 alkyl) 4 + salts. Pharmaceutically acceptable salts of the compounds of this invention include those derived from pharmaceutically acceptable inorganic and organic acids and bases. Examples of such acid salts include: acetate, adipate, alginate, aspartate. benzoate, benzenesulfonate, bisulfate, butyrate, citrate, camphorate, camphorsulfonate, cyclopentanepropionate, digluconate, dodecylhydrogensulfate. dodecylsulfate, ethanesulfonate, formate, fumarate, glucoheptanoate, glycerophosphate, glycollate, hemisulfate, heptanoate, hexanoate, hydrochloride, hydrobromide. hydroiodide. 2-hydroxyethanesulfonate. lactate, maleate, malonate, methanesulfonate, 2-naphthylsulfonate, nicotinate, nitrate, oxalate, pamoate, pectinate, perchlorate. persulfate, 3-phenylpropionate. phosphate, picrate, pivalate, propionate, salicylate. succinate, sulfate, tartrate, thiocyanate, tosylate, and undecanoate. This invention also envisions the quatemization of any basic nitrogen containing groups of the compounds disclosed herein. The basic nitrogen can be quatemized with any agents known to those of ordinary skill in the art including, for example, lower alkyl halides, such as methyl, ethyl, propyl and butyl chloride, bromides and iodides; dialkyl sulfates including dimethyl, diethyl, dibutyl and diamyl sulfates; long chain halides such as decyl, lauryl, myristyl and stearyl chlorides, bromides and iodides, and aralkyl halides including benzyl and phenethyl bromides. Water or oil-soluble or dispersible products may be obtained by such quatemization. The compounds of this invention are readily prepared using conventional techniques from commercially available and cheap starting materials. The compounds of this invention are among the most readily prepared HIV protease inhibitors known at this point. Previously described HIV protease inhibitors are resulting from long synthetic sequences and contain more than six chiral centers, numerous peptide bonds and require air-sensitive reagents such as organometallic complexes to achieve their successful preparations. The relative ease of synthesis of the products described in this invention represent a marked advantage, especially for the large scale preparation of these compounds. In general. D-mannitol derivatives of formula 1 (or formula la) are readily obtained from commercially available D-mannitol or derivatives of D-mannitol through known synthetic sequences. Using standard techniques, D- (or L- mannitol) may be transformed to the desired HIV protease inhibitors according to Scheme 1, as described below; Scheme 1 illustrates the preparation of 1,2,5,6-tetrasubstituted O-benzyl D-mannitol derivatives. SCHEME 1 MANNITOL KETAL 2 KETAL 3 BENZYL MANNITOL 4 Thus D-mannitol is converted to its 3,4-monoacetonide 2 according to a known procedure (Morpain, C. and Tisserand. M, J. Chem. Soc. Perkin Trans. 1379 - 1383 (1979)). The ketal 2 is then easily alkylated on the four hydroxyl groups with different alkyl halides (mainly substituted benzyl halides) in the presence of sodium hydride in DMF to give 3 in excellent yield. The ketal group is then readily hydrolysed using methanol (MeOH) containing hydrochloric acid to provide the desired tetraalkylated D-mannitol derivative 4 in excellent yields. Scheme 2 illustrates the preparation of 1 , 6-similarly dialkylated and 2,5-similarly dialkylated derivatives. SCHEME 2 KETAL 2 R = XC^H j CE^- KETAL 5 BENZYL INTERMEDIATE 6 BENZYL MANNITOL 7 As shown in Scheme 2, the primary hydroxyl groups in ketal 2 were selectively alkylated with various alkyl halides (mainly benzyl halides) in the presence of dibutyltin oxide and cesium fluoride in toluene to afford the 1 ,6-dialkylated intermediate 5 (David, S. and Hanessian, S. Tetrahedron 4J_, 643 (1985)). The remaining secondary hydroxyl groups were alkylated with different alkyl halides (mainly benzyl halides) using the sodium hydride in DMF method to give 6. Removal of the isopropylidene group in methanolic HCl yielded the desired tetraalkylated D-mannitol devivatives 7, bearing a similar benzyl or alkyl groups at position 1 and 6 and two different substituted benzyl or alkyl groups at position 2 and 5. Scheme 3 illustrates the preparation of 1,2,5-tri-O-substituted benzyl-D-mannitol derivatives. SCHEME BENZYL INTERMEDIATE 8 BENZYL MANNTTOL 9 R = ZC H 4 CH 2 - BENZYL INTERMEDIATE 8 BENZYL MANNITOL 10 Thus, the alkylation promoted by silver oxide allows the selective alkylation of one of the two hydroxyl groups, leading to a tri-substituted D-mannitol derivative 9 (Bouzide A. et al, Tet. Letters vol. 38. p. 5945 - 5948 (1997)). The benzyl intermediate 8 can in turn be further alkylated using sodium hydride in dimefhylformamide to provide, after deprotection of the isopropylidene group derivative 10 bearing as many as three different groups. Scheme 4 illustrates the preparation of 1.2,5, 6-tetra-O-substituted benzyl-D-mannitol derivatives with four different benzyl groups. The benzyl group can be substituted with one or more substituents which, in some cases, can be further transformed into different functional groups. SCHEME 4 MANNITOL DIKETAL 12 BENZYL T IE MEDLATE 13 BE ZYL INTERMEDIATE 14 BENZYL INTERMEDIATE 14 BENZYL INTERMEDIATE 15 BENZYL INTERMEDIATE 15 BENZYL INTERMEDIATE 16 BH^EYL INTERMEDIATE 16 BENZYL MANNπOL 17 In the above schemes one or more benzyl halides (same or different) bearing one or more substituents may be used. As can be appreciated by the skilled artisan, the above synthetic schemes are not intended to be a comprehensive list of all means by which the compounds described and claimed in this application may be synthesized. Further methods will be evident to those of ordinary skill in the art. The compounds of this invention may be modified by appending appropriate functionalities to enhance selective biological properties. Such modifications are known in the art and include those which increase biological penetration into a given biological system (e.g., blood, lymphatic system, central nervous system), increase oral availability, increase solubility to allow administration by injection, alter metabolism and alter rate of excretion. As discussed above, the novel compounds of the present invention are excellent ligands for aspartyl proteases, particularly HIV-1 protease. Accordingly, these compounds are capable of targeting and inhibiting late stage events in the replication, i.e.; the processing of the viral polyproteins by HIV encoded protease. Compounds according to this invention advantageously inhibit the ability of the HIV-1 vims to infect immortalized human T cells over a period of days, as determined by an assay of extracellular p24 antigen *■ a specific marker of viral replication (see, Meek et al., Nature, 343, pp. 90-92 (1990)). In addition to their use in the prophylaxis or treatment of HIV or HTLV infection, the compounds according to this invention may also be used as inhibitory or interruptive agents for other viruses which depend on aspartyl proteases, similar to HIV or HTLV aspartyl proteases, for obligatory events in their life cycle. Such compounds inhibit the proteolytic processing of viral polyprotein precursors by inhibiting aspartyl protease. Because aspartyl protease is essential for the production of mature virions, inhibition of that processing effectively blocks the spread of virus by inhibiting the production and reproduction of infectious virions, particularly from chronically infected cells. The compounds of this invention advantageously inhibit aspartyl proteases, thus blocking the ability of aspartyl proteases to catalyze the hydrolysis of peptide bonds. The compounds of this invention may be employed in a conventional manner for the treatment or prevention of HIV, HTLV, and other viruses, which depend on aspartyl proteases for obligatory events in their life cycle. Such methods of treatment, their dosage levels and requirements may be selected by those of ordinary skill in the art from available methods and techniques. For example, a compound of this invention may be combined with a pharmaceutically acceptable adjuvant for administration to a virally infected patient in a pharmaceutically acceptable manner and in an amount effective to lessen the severity of the viral infection. Alternatively, the compounds of this invention may be used in vaccines and methods for protecting individuals against viral infection over an extended period of time. The compounds may be employed in such vaccines either alone or together with other compounds of this invention in a manner consistent with the conventional utilization of protease inhibitors in vaccines. For example, a compound of this invention may be combined with pharmaceutically acceptable adjuvants conventionally employed in vaccines and administered in prophylactically effective amounts to protect individuals over an extended period of time against viral infections, such as HIV infection. As such, the novel protease inhibitors of this invention can be administered as agents for treating or preventing viral irrfections. including HIV infection, in a mammal. The compounds of this invention may be administered to a healthy or HIV-infected patient either as a single agent or in combination with other antiviral agents which interfere with the replication cycle of HIV. By administering the compounds of this invention with other antiviral agents which target different events in the viral life cycle, the therapeutic effect of these compounds is potentiated. For instance, the co-administered antiviral agent can be one which targets early events in the life viral cycle, such as cell entry, reverse transcription and viral DNA integration into cellular DNA. Antiviral agents targeting such early life cycle events include didanosine (ddl), zalcitabine (ddC), stavudine (d4T), zidovudine (AZT), polysulfated polysaccharides, sT4 (soluble CD4) ~ which blocks attachment or adsorption of the virus to host cells ~ and other compounds which block binding of vims to CD4 receptors on CD4 bearing T-lymphocytes. Other retroviral reverse transcriptase inhibitors, such as derivatives of AZT, may also be co-administered with the compounds of this invention to provide therapeutic treatment for substantially reducing or eliminating viral infectivity and the symptoms associated therewith. Examples of other antiviral agents include ganciclovir, dideoxycytidine, trisodium phosphonoformate, eflornifhine, ribavirin, acyclovir, alpha interferon and trimenotrexate. Additionally, non-nucleoside inhibitors of reverse transcriptase, such as TIBO or nevirapine, may be used to potentiate the effect of the compounds of this invention, as may viral uncoating inhibitors, inhibitors of trans-activating proteins such as tat or rev, antisense molecules or inhibitors of the viral integrase. These compounds may also be co-administered with other inhibitors of HIV aspartyl protease. Combination therapies according to this invention exert a synergistic effect in inhibiting HIV replication because each component agent of the combination acts on a different site of HIV replication. The use of such combinations also advantageously reduces the dosage of a given conventional anti-retroviral agent that would be required for a desired therapeutic or prophylactic effect as compared to when that agent is administered as a mono therapy. These combinations may reduce or eliminate the side effects of conventional single anti-retroviral agent therapies while not interfering with the anti-retroviral activity of those agents. These combinations reduce potential of resistance to single agent therapies, while minimizing any associated toxicity. These combinations may also increase the efficacy of the conventional agent without increasing the associated toxicity. Preferred combination therapies include the administration of a compound of this invention with AZT. 3TC, ddl, ddC or d4T. Alternatively, the compounds of this invention may also be co-administered with other HIV protease inhibitors such as Ro 31-8959 (Roche), L-735.524 (Merck), XM 323 (Dupont Merck) and A-80.987 (Abbott) to increase the effect of therapy or prophylaxis against various viral mutants or members of other HIV quasi species. We prefer administering the compounds of this invention as single agents or in combination with retroviral reverse transcriptase inhibitors, such as derivatives of AZT or other HIV aspartyl protease inhibitors. We believe that the co-administration of the compounds of this invention with retroviral reverse transcriptase inhibitors or HIV aspartyl protease inhibitors may exert a substantial synergistic effect, thereby preventing, substantially reducing, or completely eliminating viral infectivity and its associated symptoms. The compounds of this invention can also be administered in combination with immunomodulators (e.g., bropirimine, anti-human alpha interferon antibody, IL-2, GM-CSF, methionine enkephalin. interferon alpha, diethyldithiocarbamate, tumor necrosis factor, naltrexone and rEPO); antibiotics (e.g.. pentamidine isethionate) or vaccines to prevent or combat infection and disease associated with HIV infection, such as AIDS and ARC. When the compounds of this invention are administered in combination therapies with other agents, they may be administered sequentially or concurrently to the patient. Alternatively, pharmaceutical or prophylactic compositions according to this invention may be comprised of a combination of an aspartyl protease inhibitor of this invention and another therapeutic or prophylactic agent. Although this invention focuses on the use of the compounds disclosed herein for preventing and treating HIV infection, the compounds of this invention can also be used as inhibitory agents for other viruses that depend on similar aspartyl proteases for oMigatory events in their life cycle. These viruses include, but are not limited to other AIDS-like diseases caused by retrovimses, such as simian immunodeficiency viruses, HIV-2, HTLV-I and HTLV-II. In addition, the compounds of this invention may also be used to inhibit other aspartyl proteases and, in particular, other human aspartyl proteases including renin and aspartyl proteases that process endothelin precursors. Pharmaceutical compositions of this invention comprise any of the compounds of the present invention, and pharmaceutically acceptable salts thereof, with any pharmaceutically acceptable carrier, adjuvant or vehicle. Pharmaceutically acceptable carriers, adjuvants and vehicles that may be used in the pharmaceutical compositions of this invention include, but are not limited to ion exchangers, alumina, aluminum stearate. lecithin, serum proteins, such as human serum albutin, buffer substances such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes, such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-based substances, polyethyleneglycol, sodium carboxymethylcellulose, polyacrylates. waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycol and wool fat. The pharmaceutical compositions of this invention may be administered orally, parenterally by inhalation spray, topically, rectally, nasally, buccally, vaginally or via an implanted reservoir. We prefer oral administration or administration by injection. The pharmaceutical compositions of this invention may contain any conventional non-toxic pharmaceutically acceptable carriers, adjuvants or vehicles. The term "parenteral" as used herein includes subcutaneous, intracutaneous, intravenous, intramuscular, intra-articular, intrasynovial. intrastemal. intrathecal, intralesional and intracranial injection or infusion techniques. The pharmaceutical compositions may be in the form of a sterile injectable preparation, for example, as a sterile injectable aqueous or oleaginous suspension. This suspension may be formulated according to techniques known in the art using suitable dispersing or wetting agents (such as, for example, Tween 80) and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non- toxic parenterally acceptable diluent or solvent, for example, as a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are mannitol. water. Ringer's solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose, any bland fixed oil may be employed including synthetic mono- or diglycerides. Fatty acids, such as oleic acid and its glyceride derivatives are useful in the preparation of injectables, as are natural pharmaceuticallly-acceptable oils, such as olive oil or castor oil, especially in their polyoxyethylated versions. These oil solutions or suspensions may also contain a long-chain alcohol diluent or dispersant, such as Ph. Helv. or a similar alcohol. The pharmaceutical compositions of this invention may be orally administered in any orally acceptable dosage form including, but not limited to, capsules, tablets, and aqueous suspension and solutions. In the case of tablets for oral use, carriers that are commonly used include lactose and com starch. Lubricating agents, such as magnesium stearate, are also typically added. For oral administration in a capsule form, useful diluents include lactose and dried com starch. When aqueous suspensions are administered orally, the active ingredient is combined with emulsifying and suspending agents. If desired, certain sweetening and/or flavoring and/or coloring agents may be added. The pharmaceutical compositions of this invention may also be administered in the form of suppositories for rectal administration. These compositions can be prepared by mixing a compound of this invention with a suitable non-irritating excipient which is solid at room temperature but liquid at the rectal temperature and therefore will melt in the rectum to release the active components. Such materials include, but are not limited to, cocoa butter, beeswax, and polyethylene glycols. Topical administration of the pharmaceutical compositions of this invention is especially useful when the desired treatment involves areas or organs readily accessible by topical application. For application topically to the skin, the pharmaceutical composition should be formulated with a suitable ointment containing the active components suspended or dissolved in a carrier. Carriers for topical administration of the compounds of this invention include, but are not limited to, mineral oil, liquid petroleum, white petroleum, propylene glycol. polyoxy- ethylene polyoxypropylene compound, emulsifying wax and water. Alternatively, the pharmaceutical compositions can be formulated with a suitable lotion or cream containing the active compound suspended or dissolved in a carrier. Suitable carriers include, but are not limited to, mineral oil, sorbitan monostearate, polysorbate 60, cetyl esters wax cetearyl alcohol. 2-octyldodecanol, benzyl alcohol and water. The pharmaceutical compositions of this invention may also be topically applied to the lower intestinal tract by rectal suppository formulation or in a suitable neat formulation. Topically-transdermal patches are also included in this invention. The pharmaceutical compositions of this invention may be administered by nasal aerosol or inhalation. Such compositions are prepared according to techniques well-known in the art of pharmaceutical formulation and may be prepared as solutions in saline employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, fluorocarbons, and/or other solubilizing or dispersing agents known in the art. Dosage levels of between about 0.01 and about 25 mg/kg body weight per day, preferably between about 0.5 and about 25 mg/kg body weight per day of the active ingredient compound are useful in the prevention and treatment of viral infection, including HIV infection. Typically, the pharmaceutical compositions of this invention will be administered from about 1 to about 5 times per day or alternatively, as a continuous infusion. Such administration can be used as a chronic or acute therapy. The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the patient treated and the particular mode of administration. A typical preparation may contain from about 5% to about 65% active compound (w/w). Preferably, such preparations may contain from about 20% to about 65% active compound. Upon improvement of a patient ' s condition, a maintenance dose of a compound, composition or combination of this invention may be administered if necessary. Subsequently, the dosage or frequency of administration, or both, may be reduced, as a function of the symptoms, to a level at which the improved condition is retained. When the symptoms have been alleviated to the desired level, treatment should cease. Patients may, however, require intermittent treatment on a long-term basis, upon any recurrence of disease symptoms. As the skilled artisan will appreciate, lower or higher doses than those recited above may be required. Specific dosage and treatment regimen for any particular patient will depend upon a variety of factors, including the activity of the specific compound employed, the age, body weight, general health status, sex. diet, time of administration, rate of excretion, drug combination, the severity and course of the infection, the patient's disposition to the infection and the judgment of the treating physician. The compounds of this invention are also useful as commercial reagents which effectively bind to aspartyl proteases, particularly HIV aspartyl protease. As commercial reagents, the compounds of this invention, and their derivatives, may be used to block proteolysis of a target peptide, such as an aspartyl protease, or may be derivatized to bind to a stable resin as a tethered substrate for affinity chromatography applications. These and other uses which characterize commercial aspartyl protease inhibitors will be evident to those of ordinary skill in the art. Enzymatic assay for determining the inhibition constant (Ki) of synthetic compounds prepared against the HIV protease This is a fluorometric assay based on the cleavage by protease of a substrate carrying a donor group (EDANS, excitation at 340 nM and emission at 490 nM) and an acceptor group (DABCYL) on each side of the cleavage site, interacting together through fluorescence resonance energy transfer (FRET). Cleavage of the substrate by protease stops energy exchange between the two groups, resulting in a time-dependent increase in fluorescence intensity that is linearly related to the extent of substrate hydrolysis. The enzymatic assay is done at 30°C in a spectrophotometer microcuvet, in a total volume of 400 μL. The apparatus used for readings is a UV-visible Cary 1 spectrophotometer made by Varian. The reaction is run first in the absence of protease inhibitors for 2 min, using 355 μL of buffer at pH 4.7 (sodium acetate 100 mM. NaCl 1 M, EDTA 1 mM. DTT 1 rhM, dimethylsulfoxide 10%, and BSA 1 mg/mL). 40 μL of substrate H-2930 from Molecular Probes (final concentration 10 mM) and 5 μL of recombinant HIV-1 protease (final concentration 18.3 nM) purchased from Bachem Bioscience. Fluorescence readings at 490 nM are taken continuously during the reaction, allowing determination of the enzyme ' s initial velocity (v„). At the end of the 2 min incubation, the potential inhibitor at a defined concentration in a volume of 2 mL is added to the reaction, and fluorescence readings are taken for another 2 min, allowing determination of enzyme velocity (v,) in the presence of the inhibitory compound. Several concentrations of the putative inhibitors are tested in the assay. After calculation of v„ and v„ the inhibition constant (Ki) of the compound is determined using the equation of Henderson : Vo [I] where Ki ann = 1 + -^— Ki = app vi κi a a c p D p - l + rrsi and [ I ] = inhibitor concentration, [ S ] = substrate concentration, Km = Michaelis-Menten constant, Ki app = apparent Ki Note that the Michaelis-Menten constant of HIV protease is determined by running the assay without inhibitors, using several concentrations of substrate, and plotting the results as a Cornish- Bowden graph with the ratio substrate concentration / velocity as the ordinate and substrate concentration as the abscissa. The compounds listed in Table 1 were prepared by following Schemes 1, 2 or 3 above. The activities of the compounds are also listed in the same table demonstrating their potential usefulness. In Table 1 are shown compounds of formula 1 (or formula la), as defined above. wherein R,, R,. R 3 , R 4 , the same or different, denote a benzyl group of formula wherein Z is a substituent as shown in table 1 and wherein n, which may be 0, 1, 2, 3, 4 or 5 indicates the number of substituents on the phenyl ring, e.g. in the table if Z is fluorine and the phenyl ring has two fluorine atoms (i.e. n = 2) this is shown in table 1 as 2,4-F, (the numbers 2 and 4 indicating the position of the fluorine substituents on the phenyl ring). Unless indicated otherwise in Table 1, n is 1 for each of R,, R,, R 3 and R 4 ; for example, for compound number 1, since n is 0 for each R„ R 2 , R 3 and R 4 , there is no Z substituent i.e. each R,, R 2 , R 3 and R 4 is an unsubstituted benzyl group. Table 1. Derivatives of benzylated D-mannitol Table 2 shows compounds of formula 1 (or formulala), as defined above, wherein R,, R,, R 3 , R 4 , the same or different, each denotes a group of formula -CH 2 -Z, wherein Z, is a substituent as shown in table 2. Table 2. Tetra-substituted D-mannitol derivatives. Table 3 shows compounds of formula 1 (or formula la), as defined above, wherein R,, R,, R 3 , R 4 , each denotes a substituent as shown in table 3. Table 3. Di- and tri-substituted D-mannitol derivatives. The following two structures represent 1.6-dideoxy-mannitol derivatives which are described in examples 99 and 100. no 11 1 no. 1 12 In the description herein, the following abbreviations are used: Designation Reagent or Fragment AZT zidovudine Bn benzyl CHC1 3 chloroform H,C1, dichloromethane DMF dimethylformamide EDC l-(3-dimethylaminopropyl)-3-ethylcarbodiimide Et ethyl EtOAc ethyl acetate EtOH ethyl alcohol IL-2 interleukin-2 MeOH methyl alcohol rEPO recombinant erythropoietin tert-Bu tert-butyl TFA trifluoroacetic acid THF tetrahydrofuran Triτyl triphenylmethyl EXAMPLES D-Mannitol was purchased from Aldrich CO. Canada. The following examples are for the purpose of illustration only and are not to be constmed as limiting the scope of the invention in any way. When an example relates to the preparation of a compound identified in table 1, 2, or 3 above (or in table 4 below), the compound number used in these tables will appear after the name of the compound prepared in accordance to the example. Materials and Methods Analytical thin layer chromatography (TLC) was carried out with 0.25 mm silica gel E. Merck 60 F 254 plates and eluted with the indicated solvent systems. Preparative chromatography was performed either by flash chromatography, using Silica Gel 60 (EM Science) with the indicated solvent systems and a positive nitrogen pressure to allow proper elution, or by thick layer chromatography, again employing E. Merck 60 F 254 plates of 0.5. 1.0. or 2.0 mm thickness. Detection of the compounds was carried out by exposing eluted plates, analytical or preparative, to UV light and treating analytical plates witb a 2% / anisaldehyde solution in ethanol containing 1% acetic acid and 3% sulfuric acid, followed by heating, unless otherwise indicated. Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AMX 500 equipped with a reversed or QNP probe. Samples were dissolved in deuterochloroform (CDC1 3 ), deuteroacetone (acetone-d 6 ) or deuterated dimethylsulfoxide (DMSO-d 6 ) for data acquisition using tetramethylsilane (TMS) as internal standard. Chemical shifts are expressed in parts per million (ppm), the coupling constants J are expressed in hertz (Hz) and multiplicities (denoted as s for singlet, d for doublet, dd for doublet of doublets, t for triplet, q for quartet, m for multiplet. and br for broad). The number of hydrogens listed for all C,-symetry compounds is half of that present in the molecule. The following compounds were prepared from a derivative of D-mannitol using the procedures summarized in Scheme 1, 2 and 3. Example 1. Preparation of 3,4-0-isopropyIidene-D-mannitol A suspension of D-mannitol (125 g, 687 mmol) in dry acetone (1.5 L) containing sulfuric acid (12.5 mL) was stirred at room temperature for 24 h. Neutralization with an aqueous solution of NH 4 OH (33%, 44 mL) and sodium carbonate (78 g) and evaporation gave a solid that was solubilized in ethanol with vigorous stirring. The mixture was filtered and concentrated to give the crude triacetonide. To the crude acetonide was added AcOH (2 L) in H,O (1 L). The reaction was heated to 40°C for 1.5 h and then the solvent was removed in vacuo. The residue was suspended in acetone (1 L), filtered and concentrated to give a white solid. The solid was purified by recrystallization from acetone to give the desired monoacetonide (66.8%). Η NMR (CDC1 3 ): 1.38 (s, 6H), 1.60 (s, 2H), 2.04 (s, 2H), 3.70 - 4.00 (m, 8H). Example 2. Preparation of l,6-di-0-benzyl-3,4-O-isopropylidene-D-mannitol To a solution of 3,4-O-isopropylidene-D-mannitol (222 mg, 1 mmol), obtained as in example 1, in toluene (20 mL) was added dibutyltin oxide (500 mg, 2 mmol) and the mixture was heated with azeotropic removal of water for 2 h using a Dean Stark apparatus. The solvent was removed in vacuo and the resulting white solid was dissolved in DMF (10 mL). Cesium fluoride (456 mg, 3 mmol) was added with heating at 50°C until the solution was homogeneous. The solution was cooled to room temperature and benzyl bromide (261 μL, 2.2 eq.) was added in one portion. The resulting suspension was heated at 60°C for 1 h, cooled and stirred at room temperature for an additional 16 h. The reaction mixture was diluted with brine (20 mL) and extracted twice with EtOAc. The organic layer was dried over magnesium sulfate and concentrated in vacuo. Purification by flash chromatography eluting with 30% EtOAc in hexane yielded 65% of the title compound. •H NMR (CDCI 3 ): 1.35 (s, 6H), 3.44 (m, 2H), 3.60 (m, 2H), 3.75 (d, J = 3.1, 2H), 3.80 (m, 2H), 3.92 (d, J = 3.0 , 2H). 4.60 (s. 4H), 7.25 - 7.34 (m. 10H). Example 3. Preparation of 1,2,5,6-tetra-O-benzyl-D-mannitol (compound no. 1) To a solution of 3,4-O-isopropylidene-D-mannitol (11 1 mg, 0.5 mmol) as obtained from example 1 in DMF (5 mL) was added sodium hydride (72 mg, 3.0 mmol) in portions. The slurry was stirred at room temperature for 10 min. Benzyl bromide (513 mg. 3.0 mmol) dissolved in DMF (1 mL) was added dropwise. The reaction mixture was stirred at room temperature overnight, then quenched by the dropwise addition of IN HCl (10 mL). The resulting mixture was extracted twice with EtOAc (10 mL). The organic layer was dried over magnesium sulfate and then concentrated. Without any further purification, the residue was stirred overnight at room temperature in 3 mL of MeOH containing 150 μL AcCl. Afterwards the mixture was diluted with a saturated sodium bicarbonate solution (0.5 mL), extracted with EtOAc (20 mL) and concentrated in vacuo. The residue was purified by flash chromatography eluting with 20% EtOAc in hexane affording a 81% yield of 1,2,5,6-tetra-O-benzyl-D-mannitol. Η NMR (CDC1 3 ): 3.07 (d. J = 5.5, 2H), 3.70 (dd, J = 9.3, 3.7, IH), 3.72 (m, 2H), 3.99 (t, J = 5.5, IH), 4.57 (s, 4H), 4.61 (d, J = 1 1.2, 2H), 4.75 (d, J = 11.2, 2H), 7.35 (m, 20H). Example 4. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-cyanobenzyl)-D-mannitol (compound no. 14) To a solution of l ,6-di-O-benzyl-3.4-O-isopropylidene-D-mannitol (402 mg, 1.0 mmol), obtained as in example 2, in DMF (10 mL) was added portionwise sodium hydride (72 mg, 3.0 mmol). After stirring 10 min. -cyanobenzyl bromide (588 mg, 3.0 mmol) was added dropwise and the reaction mixture was stirred at room temperature for 12 h. The reaction was quenched by the addition of IN HCl and extracted twice with EtOAc. The organic layer was dried over magnesium sulfate and the residue obtained by evaporation in vacuo was taken up in 5% HCl methanolic solution (6 mL). After 5 h of stirring at room temperature, the solvent was evaporated in vacuo and the residue was purified by flash chromatography using 30% EtOAc in hexane to afford 70% of the title compound. 'H NMR (CDC1 3 ): 3.00 (d, J = 5.7, IH), 3.67 (m, IH), 3.86 (m, 2H), 3.96 (m, IH), 4.54 (s, 2H), 4.65 (d, J = 12.6, IH), 4.76 (d, J = 12.6, IH, 7.20 - 7.60 (m, 9H). Example 5. Preparation of l,2,5,6-tetra-O-(4-trifluoromethylbenzyl)-D-mannitol (compound no. 11) Following the indications found in example 3, the title compound was prepared by reacting 3,4-O-isopropylidene-D-mannitol with 4-trifluoromethyl benzyl chloride in a 72% yield. Η NMR (CDC1 3 ): 3.00 (s, IH), 3.72 (dd, J = 10.3, 4.9, IH), 3.82 (m, 2H), 4.02 (d, J = 6.5, IH), 4.60 (s, 2H), 4.68 (d, J = 1 1.8, IH), 4.78 (d, J = 11.8, IH), 7.42 (m, 4H), 7.56 (m, 4H). Example 6. Preparation of l,2,5,6-tetra-O-(4-cyanobenzyl)-D-mannitol (compound no. 12) As described in example 3, the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with 4-cyanobenzyl bromide in a 65% yield. Η NMR (CDC1 3 ): 2.06 (d, J = 5, IH), 3.74 (m, IH), 3.80 (m, 2H), 4.00 (m, IH), 4.61 (s, 2H), 4.70 (d, J = 12.9, IH), 4.82 (d, J = 12.9, IH), 7.40 (m, 4H), 7.60 (m, 4H). Example 7. Preparation of l,2,5,6-tetra-O-(4-methylbenzyI)-D-mannitol (compound no. 50) As described in example 3, the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with 4-methylbenzyl bromide in a 65% yield. Η NMR (CDClj): 2.30 (s, 3H), 2.31 (s, 3H), 2.99 (br, IH), 3.63 (dd, J = 5.1, 10.2. IH), 3.72 (m, 2H), 3.93 (d, J = 6.4, IH), 4.48 (s, 2H), 4.51 (d, J = 11.3, IH), 4.65 (d, J = 11.3, IH), 7.07 (d, J = 8.3, 2H), 7.09 (d, J = 8.9, 2H), 7.18 (d, J = 7.8, 2H), 7.19 (d, J = 7.5, 2H). Example 8. Preparation of l,2,5,6-tetra-O-(3,5-dihydroxybenzyι)-D-mannitol (compound no. 65) Step A. l,2,5,6-tetra-O-(3,5-dibenzyloxybenzyl)-D-mannitol (compound no. 66) As described in example 3, the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with 3,5-dibenzyloxybenzyl chloride providing the desired l,2,5,6-tetra-O-(3,5-dibenzyloxybenzyl)-D-mannitol in a 9% yield. Step B. l,2.5,6-tetra-O-(3,5-dihydroxybenzyl)-D-mannitol The product obtained in step A of this example was hydrogenolyzed in EtOAc containing 5% palladium on charcoal and one drop of pyridine. Purification of the crude product by flash chromatography eluting with 15%) MeOH in CH,C1, provided the desired product (29%). 'H NMR (CDC1 3 ): 3.63 - 3.68 (m, 4H), 3.76 (bs, 2H), 3.86 (d, 10, 2H), 3.91 (t, J = 6.0, 2H), 4.42 (s, 4H), 4.48 (d, J = 11.4, 2H), 4.68 (d, J = 1 1.9, 2H), 6.25 (s, 4H), 6.38 (s, 8H), 8.13 (s, 8H). Example 9. Preparation of l,2,5,6-tetra-0-(4-fluorobenzyl)-D-mannitol (compound no. 52) As described in example 3, the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with 4-fluorobenzyl bromide in a 73%) yield. Η NMR (CDCI 3 ): 2.98 (d, J = 5.4, IH), 3.62 - 3.75 (m, 3H), 3.92 (t, J = 5.6, IH), 4.49 (s, 2H), 4.55 (d, J = 11.3, IH). 4.67 (d, J = 1 1.8, IH), 6.99 (q, J = 8.7, 4H), 7.26 (d, J = 6.8. 4H). Example 10. l,2,5,6-tetra-O-(4-pyridylmethyl)-D-mannitol (compound no. 77) As described in example 3. the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with 4-pyridylmethyl chloride hydrochloride in a 10% yield. Η NMR (CDC1 3 ): 2.30 (s. IH), 3.68 (dd. J = 7.1. 1 1.1, IH). 3.80 (d, J = 9.2, 2H), 4.22 (d, J = 3.5, IH), 4.50 (s, 2H), 4.60 (d, J = 13.1, IH), 4.80 (d, J = 13.4, IH), 7.20 (d, J = 7.19 (d, J = 5.3, 2H), 7.22 (d, J = 5.3, 2H). 8.51 (d, J = 5.1, 2H), 8.53 (d, J = 5.1, 2H). Example 11. 1,2,5,6-tetra-O-allyl-D-mannitol (compound no. 78) As described in example 3, the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with allyl bromide in a 50% yield. Η NMR (CDCI 3 ): 3.10 (br, IH), 3.60 - 3.75 (m, 3H), 3.88 (d, J = 5.8, IH), 4.02 (d, J = 5.5, 2H), 4.10 (m, IH), 4.22 (m. IH). 5.17 (t, J = 11.1, 2H), 5.27 (dd, J = 8.5, 17.3, 2H), 5.93 (m, 2H). Example 12. 1,2,5,6-tetra-O-methyI-D-mannitol (compound no. 81) As described in example 3. the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with methyl iodide in a 15% yield. Η NMR (CDC1 3 ): 1.54 (br. IH), 3.31 (s, 3H), 3.42 (s, 3H), 3.40 - 3.48 (m, IH), 3.58 (dd. J = 7.4, 10.5. lH), 4.04 (m, IH). Example 13. 1,2,5,6-tetra-O-cyclopropylmethyl-D-mannitol (compound no. 79) As described in example 3, the title compound was prepared by reacting 3,4-O- isopropylidene-D-mannitol with cyclopropylmethyl bromide in a 45% yield. Η NMR (DMSO-d 6 ): 0.15 (m, 4H), 0.43 (m, 4H), 0.97 (d, J = 6.4, 2H), 3.20 - 3.40 (m, 6H), 3.55 (d, J = 8.5, IH), 3.71 (d, J = 10.4, IH), 4.22 (br, IH). Example 14. Preparation of l,6-di-0-benzyI-2,5-di-0-(4-carbomethoxybenzyl)-D- mannitol (compound no. 19) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3.4-O-isopropylidene-D-mannitol with 4-trifluoromethylbenzyl bromide in a 75% yield. Η NMR (CDCI 3 ): 3.04 (d, J = 5.8. IH), 3.68 (m, IH), 3.75 (m, 2H), 3.90 (s, 3H), 4.00 (m, IH), 4.52 (s, 2H), 4.64 (d, 12.5, IH), 4.77 (d, J = 12.3, IH), 7.25 (m, 5H), 7.36 (d. J = 7.7, 2H), 7.98 (d, J = 7.8, 2H). Example 15. Preparation of l,6-di-0-benzyl-2,5-di-O(4-benzyloxybenzyI)-D- mannitol (compound no. 6) As described in example 4. the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 4-benzyloxybenzyl chloride in a 62% yield. Η NMR (CDC1 3 ): 3.02 (d, J = 6.3, IH), 3.65 (dd, J = 10.9, 5.2, IH), 3.73 (m, 2H), 3.93 (t, J = 6.2. IH), 4.51 (d. J = 11.2, IH), 4.54 (s, 2H), 4.64 (d, J = 1 1.2, IH). 5.03 (s, 2H), 6.90 (d, J = 7.4, 2H). 7.22 (d, J = 8.6, 2H), 7.25 - 7.44 (m, 10H). Example 16. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-hydroxybenzyl)-D-mannitol (compound no. 2) A mixture of 1.6-di-O-benzyl-2,5-di-O-(4-benzyloxybenzyl)-D-mannitol, obtained as in example 15, (97 mg, 0.10 mmol) in MeOH (1 mL), pyridine (8.0 mg, 0.1 mmol) and 5% palladium on charcoal (70 mg) was hydrogenated at atmospheric pressure and room temperature for 1 h. The reaction mixture was filtered and concentrated in vacuo. Flash chromatography on silica gel eluting with 50% EtOAc in hexane afforded the title compound in 87% yield. Η NMR (CDCI 3 ): 3.45 (d, J = 5.3. IH), 3.64 (dd, J = 11.4, 5.5. IH), 3.71 (d, J = 5.2, IH), 3.75 (dd, J = 1 1.2. 5.5. IH), 4.00 (t, J = 5.3, IH), 4.40 (d, J = 5.3, IH), 4.52 (s, 2H), 4.60 (d, J = 1 1.0, IH). 6.37 (s, IH), 6.62 (d, J = 7.5, 2H), 7.06 (d, J = 7.5. 2H), 7.30 (m. 5H). Example 17. Preparation of l,6-di-0-benzyl-2,5-di-O-(3-benzyloxybenzyI)-D- mannitol (compound no. 67) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 3-benzyloxybenzyl bromide in a 62% yield. Η NMR (CDC1 3 ): 3.02 (d, J = 5.0, IH), 3.68 (dd, J = 6.0, 1 1.0, IH), 3.74 (d, J = 7.7, 2H), 3.97 (t, J = 5.0. IH), 4.50 (s, 2H), 4.60 (d. J = 1 1.0, IH), 4.70 (d, J = 1 1.0, IH), 5.03 (s. 2H), 6.90 - 7.40 (m, 14H). Example 18. Preparation of l,6-di-0-benzyl-2,5-di-O-(4-trifluoromethylbenzyl)-D- mannitol (compound no. 22) As described in example 4, the title compound was prepared by reacting 1,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 4-trifluoromefhylbenzyl bromide in a 76% yield. Η NMR (CDCI 3 ): 3.05 (d, J = 5.5, IH), 3.67 (m, IH), 3.77 (m, 2H), 4.00 (s, IH), 4.54 (s, 2H), 4.65 (d. J = 12.4. IH), 4.77 (d, J = 11.9. IH), 7.25 - 7.40 (m, 9H). Example 19. Preparation of l,6-di-O-benzyI-2,5-di-O-(4-methylbenzyl)-D-mannitoI (compound no. 24) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3.4-O-isopropylidene-D-mannitol with 4-methylbenzyl bromide in a 89% yield. Η NMR (CDCI 3 ): 2.31 (s, 3H). 3.00 (s. IH), 3.64 (m, IH), 3.74 (m, 2H), 3.90 (s, IH), 4.53 (s, 2H), 4.54 (d, J = 10.7, IH), 4.67 (d, J = 11.2, IH), 7.10 - 7.35 (m, 9H). Example 20. Preparation of l,6-di-0-benzyI-2,5-di-O-(4-bromobenzyl)-D-mannitoI (compound no. 18) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 4-bromobenzyl bromide in a 82% yield. Η NMR (CDCI 3 ): 3.02 (d, J = 5.6, IH), 3.65 (m, IH), 3.72 (d, J = 7.2, 2H), 3.93 (t, J = 6.1, IH), 4.51 (d, J = 7.4, IH), 4.53 (s, 2H), 4.64 (d, J = 12.2, IH), 7.15 d, J = 7.7, 2H), 7.30 (m, 5H), 7.40 (d, J = 7.7, 2H). Example 21. Preparation of l,6-di-O-benzyl-2,5-di-O-(4-chlorobenzyl)-D-mannitol (compound no. 17) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 4-chlorobenzyl bromide in a 85% yield. 'H NMR (CDCI 3 ): 3.08 (br, IH), 3.61 (m, IH), 3.70 - 3.81 (m, 2H), 4.50 (s, 2H), 4.54 (d. J = 11.5, IH), 4.68 (d, J = 11.5. IH), 7.10 - 7.42 (m, 9H). Example 22. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-fluorobenzyl)-D-mannitol (compound no. 16) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3.4-O-isopropylidene-D-mannitol with 4-fluorobenzyl bromide in a 71% yield. »H NMR (CDC1 3 ): 3.01 (d, J = 4.5, IH), 3.63 (m, IH), 3.75 (m, 2H), 3.93 (t, J = 5.1. IH), 4.53 (s, 2H), 4.54 (d, J = 1 1.5, IH), 4.66 (d, J = 1 1.7, IH), 6.99 (m, 4H), 7.25 (m, 5H). Example 23. Preparation of l,6-di-0-benzyl-2,5-di-O-(2,6-difluorobenzyl)-D- mannitol (compound no. 25) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3.4-O-isopropylidene-D-mannitol with 2,6-difluorobenzyl bromide in a 92% yield. •H NMR (CDCI 3 ): 2.94 (d, J = 5.5, IH), 3.66 (dd, J = 10.1, 5.5, IH), 3.77 (m, 2H), 3.88 (t, J = 6.5, IH), 4.56 (s, 2H), 4.66 (d, J = 10.8, IH), 4.86 (d, J = 1 1.0, IH), 6.85 (m, 2H), 7.30 (m. 6H). Example 24. Preparation of l,6-di-0-benzyl-2,5-di-O-(2,4-difluorobenzyl)-D- mannitol (compound no. 23) As described in example 4, the title compound was prepared by reacting 1,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 2.4-difluorobenzyl bromide in a 88% yield. Η NMR (CDC1 3 ): 2.97 (d, J = 5.8, IH), 3.67 (dd, J = 1 1.1, 6.6, IH), 3.75 (d, J = 7.4, 2H), 3.91 (dd. J = 6.2. 1 1.5. IH), 4.55 (s. 2H), 4.60 (d. J = 12.0, IH), 4.73 (d, J = 1 1.8 , IH). 6.79 (m. 2H), 7.31 (m, 6H). Example 25. Preparation of l,6-di-0-benzyl-2,5-di-O-(2-fluorobenzyl)-D-mannitol (compound no. 21) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide in a 93% yield. 'H NMR (CDCI 3 ): 3.02 (d, J = 5.6, IH), 3.69 (dd, J = 10.9, 5.4, IH), 3.78 (m, 2H), 3.95 (t, J = 6.1. IH), 4.54 (s, 2H), 4.65 (d. J = 11.7, IH), 4.78 (d, J = 11.9, IH), 7.00 (t, J = 9.3, IH), 7.07 (t, J = 7.5. IH), 7.27 (m, IH), 7.31 (s, 5H), 7.36 (m, IH). Example 26. Preparation of l,6-di-O-benzyI-2,5-di-0-(3-fluorobenzyI)-D-mannitol (compound no. 20) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 3-fluorobenzyl bromide in a 85% yield. •H NMR (CDCI 3 ): 3.05 (d, J = 5.6, IH), 3.67 (dd, J = 13.1, 7.2, IH), 3.75 (d, J = 6.9, 2H), 3.96 (t. J = 5.9. IH), 4.54 (s, 2H), 4.58 (d, J = 11.5, IH), 4.70 (d, J = 11.5, IH), 6.93 (m, IH), 7.03 (m, 2H), 7.28 (m, IH), 7.30 (s, 5H). Example 27. Preparation of l,6-di-O-benzyl-2,5-di-0-(pentafluorobenzyl)-D- mannitol (compound no. 15) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with pentafluorobenzyl bromide in a 23% yield. Η NMR (CDCI 3 ): 2.85 (d, J = 5.5, IH), 3.62 (m, IH), 3.77 (m, 2H), 3.81 (t, J = 5.3, IH), 4.54 (s, 2H), 4.67 (d, J = 1 1.1, IH), 4.82 (d, J = 10.9, IH), 7.30 (m, 5H). Example 28. Preparation of l,2,5-tri-O-(4-fluorobenzyl)-6-O-(3,5-dihydroxybenzyl)- D-mannitol (compound no. 72) Step A. l-O-(3,5-dibenzyloxybenzyl)-3,4-O-isopropylidene-D-mannitol Following the indications of example 2, but carrying out the reaction with 3,5- dibenzyloxybenzyl chloride at room temperature instead of 60°C, the monoalkylated mannitol derivative was isolated in 29%) yield after purification by flash chromatography eluting with 50% EtOAc in hexane. Η NMR (CDCI 3 ): 1.38 (s, 6H). 3.57 - 3.95 (m. 10H). 4.54 (d, J = 5.8, 2H). 5.04 (s, 4H), 6.58 (s. IH), 6.62 (s, 2H). 7.34 - 7.44 (m, 10H). Step B. 1.2,5-tri-O-(4-fluorobenzyl)-6-O-(3,5-dibenzyloxybenzyl)-D-mannitol (compound no. 71) The product of step A of this example was alkylated with 4-fluorobenzyl bromide (4 eq.) using the conditions described in example 3. Purification by flash chromatography eluting with 30%) EtOAc in hexane provided 50% of the desired product. Η NMR (CDCI 3 ): 2.90 (br s, 2H), 3.61 - 3.74 (m, 6H), 3.93 (t, J = 5.4, 2H), 4.47 (d, J = 6.8, 4H), 4.52 - 4.55 (m. 2H), 4.66 (t, J = 12.2, 2H), 4.98 (s, 4H), 6.55 (s, IH), 6.58 (s, 2H), 6.96 (p, J = 8.9, 6H), 7.23 - 7.39 (m, 16H). Step C. 1.2,5-tri-O-(4-fluorobenzyl)-6-O-(3,5-dihydroxybenzyl)-D-mannitol The product of step B of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 50% EtOAc in hexane. The title compound (73%) was thus obtained. 'H NMR (CDCI 3 ): 3.22 (d, J = 6.5. IH), 3.26 (s, IH), 3.56 - 3.71 (m, 5H), 3.79 (d, J = 4.5, IH), 4.01 (s, IH), 4.06 (s. IH), 4.29 (d, J = 12.5. IH), 4.40 (d, J = 13.0, IH). 4.44 - 4.53 (m. 4H). 4.60 (dd, J = 4.0, 1 1.0. 2H), 6.2 (s, IH), 6.29 (s, 2H), 6.48 (s, 2H). 6.94 (q, J = 9.0. 6H), 7.21 - 7.25 (m. 6H). Example 29. Preparation of l,6-di-O-(4-carboisobutoxybenzyl)-2,5-di-0-benzyl D- mannitol (compound no. 30) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-carboisobutoxybenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4- carboisobutoxybenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 56% yield. Η NMR (CDC1 3 ): 1.01 (d, J = 7.3, 6H), 2.08 (h, J = 7.3, IH), 2.96 (d, J = 5.5, IH), 3.65 (m. IH), 3.75 (m. 2H), 3.97 (t, J = 5.8, IH), 4.10 (d, J = 7.3, 2H), 4.58 (s, 2H), 4.61 (d, J = 11.8. IH), 4.73 (d, J = 1 1.1, IH), 7.30 (m, 5H), 7.37 (d, J = 8.6. 2H), 7.99 (d. J = 7.8, 2H). Example 30. Preparation of l,6-di-0-(3-fluorobenzyl)-2,5-di-O-(benzyl)-D-mannitol (compound no 53) The alkylation of 3,4-O-isopropylidene-D-mannitol with 3-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(3-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 6. Purification by flash chromatography provided a 63 % yield. 'H NMR (CDCI 3 ): 3.08 (d, J = 7.0. IH), 3.65 (d, J = 1 1.2, IH), 3.65 - 3.70 (m, IH), 3.72 - 3.80 (m. 2H), 3.80 (d, J = 11.2, IH), 4.00 (t, J = 4.3, IH), 4.50 (s, 2H), 7.29 - 7.56 (m, 8H). Example 31. Preparation of l,6-di-O-(2-fluorobenzyl)-2,5-di-O-(3-fluorobenzyl)-D- mannitol (compound no. 57) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with 3-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 58% yield. Η NMR (CDCl j ): 3.02 (d, J = 6.0, IH), 3.65 - 3.70 (m, IH), 3.71 - 3.80 (m, 2H). 3.90 (s, IH), 4.50 (s, 2H), 4.50 (d, J = 1 1.1, IH), 4.65 (d, J = 1 1.1, IH), 6.88 - 7.40 (m, 8H). Example 32. Preparation of l,6-di-O-(2,6-difluorobenzyl)-2,5-di-0-benzyI-D- mannitol (compound no. 35) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2,6-difluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(2,6-difluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 6. Purification by flash chromatography provided a 56% yield. Η NMR (CDC1 3 ): 2.95 (d, J = 4.0, IH), 3.68 (m, 2H), 3.78 (m, IH), 3.87 (m, IH), 4.55 (d, J = 11.0, IH), 4.61 (d, J = 11.0, IH), 4.65 (d, J = 11.0, IH), 4.70 (d, J = 11.0, IH), 6.88 (m, 2H), 7.29 (m, 6H). Example 33. Preparation of l,6-di-O-benzyl-2,5-di-0-(2-naphthylmethyl)-D- mannitol (compound no. 80) As described in example 4, the title compound was prepared by reacting 1,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 2-naphthylmethyl bromide in a 88% yield. Η NMR (CDCI 3 ): 3.09 (d, J = 5.8, IH), 3.68 (m, IH), 3.77 (m, 2H), 4.03 (t, J = 6.1, IH), 4.54 (s, 2H), 4.74 (d, J = 7.4, IH), 4.86 (d, J = 11.8, IH, 7.20 - 7.80 (m, 12H). Example 34. Preparation of l,6-di-O-benzyl-2,5-di-0-allyl-D-mannitol (compound no. 82) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with allyl bromide in a 23% yield. 'H NMR (CDCI 3 ): 3.11 (d, J = 5.4, IH), 3.65 (m, 3H), 3.91 (t, J = 5.2, IH), 4.08 (dd, J = 12.6, 5.8, IH), 4.20 (dd. J = 12.5. 5.4, IH), 4.55 (s, 2H), 5.14 (d, J = 10.3, IH), 5.22 (d, J = 17.4, IH, 5.90 (m, IH), 7.30 (m, 5H). Example 35. Preparation of l,6-di-O-benzyl-2,5-di-0-cyclopropyImethyl-D-mannitol (compound no. 83) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with cyclopropylmethyl bromide in a 76% yield. 'H NMR (CDC1 3 ): 0.18 (d, J = 4.7, 2H), 0.50 (d, J = 7.5, 2H), 1.04 (m, IH), 3.26 (d, J = 5.4, IH), 3.39 (m, IH), 3.50 (m, IH), 3.65 (m, 2H), 3.90 (m, IH), 4.56 (s, 2H), 7.33 (m, 5H). Example 36. Preparation of 1 ,6-di-O-benzyl, 2,5-di-O-cinnamyl-D-mannitol (compound no. 84) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with cinnamyl bromide in a 77%) yield. Η NMR (CDCI 3 ): 3.17 (d, J = 5.5, IH), 3.68 (m, IH), 3.76 (d, J = 6.5, 2H), 3.98 (t, J = 5.5, IH), 4.26 (dd, J = 12.4, 5.8, IH), 4.35 (dd, J = 12.5,5.9, IH), 4.56 (s, 2H), 6.27 (m, IH), 6.58 (d, J = 15.7, IH), 7.21 - 7.36 (m, 10H). Example 37. Preparation of l,6-di-0-benzyI-2,5-di-O-(2-thienylmethyl)-D-mannitol (compound no. 85) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 2-thienylmethyl bromide in a 53% yield. Η NMR (CDCl j ): 2.94 (d, J - 6.0, IH), 3.64 (dd, J = 14.0, 9.0, IH), 3.75 (m, 2H), 3.90 (t, J = 8.0. IH), 4.55 (s, 2H), 4.76 (d. J = 15.0, IH), 4.90 (d, J = 11.5, IH), 6.90 - 7.30 (m, 9H). Example 38. Preparation of l,6-di-O-benzyl-2,5-di-O-(4-pyridylmethyl)-D-mannitoI (compound no. 86) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 4-pyridylmethyl chloride hydrochloride in a 23%> yield. 'H NMR (CDCLJ: 3.30 (br, IH), 3.72 (m, IH), 3.79 (m, 3H), 4.00 (d, J = 6.2, IH). 4.54 (s, 2H), 4.60 (d, J = 13.0, IH), 4.74 (d, J = 13.1, IH), 7.18 (d, J = 4.5, 2H), 7.30 (s. 5H), 8.50 (d, J = 4.5, 2H). Example 39. Preparation of l,6-di-O-benzyI-2,5-di-0-(3-pyridylmethyl)-D-mannitol (compound no. 87) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 3-pyridylmethyl chloride hydrochloride in a 25% yield. Η NMR (CDC1 3 ): 3.00 (br, IH), 3.68 (dd, J = 5.5, 10.0, IH), 3.77 (m, 2H), 3.94 (d, J = 5.5, IH), 4.54 (s, 2H), 4.60 (d, J = 12.0, IH), 4.73 (d, J = 12.0, IH), 7.20 - 7.35 (m, 6H), 7.63 (d. J = 7.5, IH), 8.52 (d, J = 5.5, 2H). Example 40. Preparation of l,6-di-0-benzyl-2,5-di-O-(2-pyridylmethyl)-D-mannitoI (compound no. 88) As described in example 4, the title compound was prepared by reacting 1 ,6-di-O-benzyl- 3,4-O-isopropylidene-D-mannitol with 2-pyridylmethyl chloride hydrochloride in a 15% yield. 'H NMR (CDCI 3 ): 3.78 (dd, J = 6.0, 10.7, IH), 3.95 (d, J = 8.7, IH), 4.06 (d, J = 7.5, IH), 4.57 (s. 2H), 4.86 (d, J = 13.8, IH), 4.93 (d, J = 13.8, IH), 7.17, (t, J = 7.0, IH), 7.20 - 7.35 (m, 6H), 7.63 (d, J = 6.5, IH), 8.51 (d, J = 4.7, 2H). Example 41. Preparation of l,6-di-0-benzyl-2,5-di-O-(4-aminobenzyl)-D-mannitol (compound no. 41) To a solution of 1 ,6-di-O-benzyl-2,5-di-O-(4-nitrobenzyl)-D-mannitol (64 mg, 0.1 mmol) prepared in example 74 in MeOH was added 5% palladium on charcoal (40 mg) and sodium borohydride (114 mg, 3.0 mmol). The reaction mixture was stirred at room temperature for 2 h. Brine (2 mL) was added and stirring was continued for 5 h. The mixture was extracted with EtOAc, dried over magnesium sulfate and concentrated in vacuo to yield (44 mg, 85%) after purification by flash chromatography. 'H NMR (CDC1 3 ): 3.04 (br. IH), 3.61 (m, IH), 3.70 (m, 2H), 3.90 (d, J = 5.9, IH), 4.43 (d, J = 1 1.0, IH), 4.53 (s, 2H), 4.60 (d, J = 1 1.0, IH), 6.57 (d, J = 8.3, 2H), 7.08 (d, J = 8.1, 2H), 7.30 (s, 5H). Example 42. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-tert- butyloxycarbonylaminobenzyl)-D-mannitol (compound no. 47) To a solution of l,6-di-O-benzyl-2,5-di-O-(4-aminobenzyl)-D-mannitol (320 mg, 0.5 mmol) from example 41 in EtOAc (2 mL) was added triethylamine (50 mg, 2.5 mmol) and 2-(tert-butoxycarbonyloxyamino)-2-phenylacetonitrile (BOC-ON) (500 mg, 2.5 mmol). The mixture was stirred for 24 h at room temperature. The mixture was evaporated in vacuo and the residue was purified by flash chromatography eluting with 30%> EtOAc in hexane, yielding the title compound in 92% yield. 'H NMR (CDCI 3 ): 1.52 (s, 9H), 3.00 (d, J = 5.5, IH), 3.62 (dd, J = 11.0, 5.5, IH), 3.71 (m, 2H), 3.91 (m, IH), 4.50 (m, 3H), 4.66 (d, J = 1 1.0, IH), 6.53 (s, IH), 7.10 (d, J = 8.0, 2H), 7.32 (m, 7H). Example 43. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-carboxamidobenzyl)-D- mannitol (compound no. 44) To a stirred solution of 1.6-di-O-benzyl-2,5-di-O-(4-cyanobenzyl)-D-mannitol (100 mg, 0.17 mmol) (prepared in example 4) in ethanol (1 mL) was added IN sodium hydroxide (0.5 mL) and the mixture was refluxed for 3 h and then cooled to 0°C. IN HCl was added dropwise until the pH of the mixture was acid. The reaction mixture was extracted with EtOAc, dried over magnesium sulfate and concentrated in vacuo. The cmde material was purified by flash chromatography eluting with 5% MeOH in methylene chloride to yield 78 % of the title compound. In addition, another fraction was found to be 1 ,6-di-O-benzyl-2- O-(4-cyanobenzyl)-5-O-(4-carboxamidobenzyl)-D-mannitol (7%). l,6-di-O-benzyl-2-O-(4-cyanobenzyl)-5-O-(4-carboxamidobenzyl)-D-mannitol (compound no. 60) Η NMR (CDC1 3 ): 3.13 (d, J = 6.0, IH), 3.16 (d, J = 8.5, IH), 3.68 - 3.72 (m, 2H), 3.73 - 3.82 (m, 4H), 4.10 - 4.14 (m, 2H), 4.54 (s, 2H), 4.55 (s, 2H), 4.63 (d, J = 13.0. 2H), 4.77 (d, J = 13.0, 2H), 5.90 (br. 4H). 6.10 (br, IH), 7.28 - 7.42 (m, 14H), 7.55 (d, J = 7.5, 2H), 7.72 (d, J = 7.0, 2H). 1 ,6-di-O-benzyl-2,5-di-O-(4-carboxamidobenzyl)-D-mannitol Η NMR (DMSO-d 6 ): 2.51 (s, lH), 3.62 (m, IH), 3.68 (m, IH), 3.80 (d, J = 6.0, IH), 3.89 (d, J = 6.0, IH), 4.50 (s, 2H), 4.60 (d, J = 12.0, IH). 7.30 (m, 5H), 7.38 (d, J = 7.8, 2H), 7.81 (d, J = 7.8, 2H), 7.92 (s, IH). Example 44. Preparation of l,6-di-0-benzyl-2,5-di-O-(4-aminomethylbenzyl 4)- mannitol (compound no. 46) A stirred solution of l,6-di-O-benzyl-2,5-di-O-(4-cyanobenzyl)-D-mannitol (100 mg, 0.17 mmol) (prepared in example 4) and lithium aluminum hydride (32 mg, 0.85 mmol) was heated at reflux for 3 h in THF. After cooling at room temperature, the reaction was treated with 2N sodium hydroxide and stirring was continued for a period of 5 h. The mixture was extracted with EtOAc and the extract was dried over sodium sulfate and concentrated in vacuo. After purification by flash chromatography eluting with 10%) MeOH in methylene chloride, the title compound was obtained in 37% yield. Η NMR (CDC1 3 ): 1.80 (br, lH), 3.04 (br, IH), 3.64 (m, IH), 3.95 (m, IH), 4.15 (m, 2H), 4.53 (s, 2H), 4.55 (d, J = 12.0, IH), 4.66 (d, J = 12.0, IH), 5.00 (s, 2H), 7.30 - 7.42 (m, 9H). Example 45. Preparation of l,6-di-O-benzyl-2,5-di-O-(4-carboxybenzyl)-D-mannitol (compound no. 43) To a solution of l,6-di-O-benzyl-2,5-di-O-(4-carbomethoxybenzyl)-D-mannitol. obtained as in example 14, (65 mg, 0.1 mmol) in MeOH (2 mL) and water (1 mL) was added sodium hydroxide (16 mg. 0.4 mmol). The reaction was stirred at room temperature for 3 h. 10%) HCl was then added until acidic pH and the mixture was extracted with EtOAc. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The residue was purified by flash chromatography eluting with 10% MeOH in methylene chloride to yield 77% of the desired title compound. In additicm, 1 ,6-di-O-beylzyl-2-O-(4- carboxybenzyl)-5-O-(4-carbomethoxybenzyl)-D-mannitol was obtained in a low yield of 5%. l,6-di-O-benzyl-2-O-(4-carboxybenzyl)-5-O-(4-carbomethoxybenzyl)-D-mannitol (compound no. 59) 'H NMR (DMSO-d 6 ): 2.58 (s, IH), 3.70 (m, IH), 3.77 (t, J = 5.0, IH), 3.85 (s, IH), 4.02 (d, J = 11.0, IH), 4.60 (s, 2H), 4.70 (d, J = 11.0, IH), 4.88 (d, J = 1 1.0, IH), 7.35 - 7.40 (m, 9H), 8.12 (d, J = 8.0, IH). l,6-di-O-benzyl-2,5-di-Of¥-carboxybenzyl)-D-mannitol Η NMR (DMSO-d 6 ): 2.60 (s, IH), 3.70 (m, IH), 3.79 (t, J = 5.0, IH), 3.88 (s, IH), 4.00 (d, J = 11.0, IH), 4.62 (s, 2H), 4.68 (d, J = 11.0, IH), 4.88 (d, J = 1 1.0, IH), 7.40 (m, 9H), 8.10 (d, J = 8.0, IH). Example 46. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-hydroxymethylbenzyl)-D- mannitol (compound no. 45) In a similar fashion as described in example 44, using 1 ,6-dibenzyl-2,5-di-O-(4- carbomethoxybenzyl)-D-mannitol. obtained as in example 14, in place of 1,6-di-O-benzyl- 2,5-di-O-(4-cyanobenzyl)-D-mannitol, was reduced to the desired product with lithium aluminium hydride in 88%> yield. 'H NMR (CDCI 3 ): 3.04 (br, IH), 3.66 (m. IH), 3.75 (m, 2H), 3.94 (m, IH), 4.54 (s, 2H), 4.57 (d, J = 12.3 IH), 4.65 (s, 2H). 4.71 (d, J = 11.5, IH), 7.30 (m, 9H). Example 47. Preparation of l,6-di-O-benzyl-2,5-di-0-(4-formylbenzyl)-D-mannitol (compound no. 49) To a solution of l,6-di-O-benzyl-2,5-di-O-4-cyanobenzyl-D-mannitol, obtained as in example 4, (126 gm, 0.2 mmol) in formic acid (2 mL) was added Raney nickel. The suspension was heated at 60-80°C for 1 hour. The reaction mixture was then filtered on Celite and the filtrate was concentrated in vacuo. The crude mixture was diluted with a solution of sodium bicarbonate and extracted with EtOAc and then methylene chloride. The combined organic layers was dried over sodium sulfate and concentrated in vacuo. Purification by flash chromatography eluting with 30% EtOAc in hexane afforded 50 mg (42%) of the title compound. Η NMR (CDCI 3 ): 3.02 (d, J = 5.5, IH), 3.70 (m, IH), 3.79 (m, 2H), 4.00 (t, J = 5.9, IH), 4.55 (s, 2H), 4.68 (d, J = 12.1, IH), 4.79 (d, J = 12.3, IH), 7.29 (m, 5H), 7.46 (d, J = 8.1, 2H), 7.81 (d, J = 9.0. 2H), 9.98 (s, IH). Example 48. Preparation of l,6-di-O-(4-methylbenzyl)-2,5-di-0-benzyI-D-mannitol (compound no. 26) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-methylbenzylbromide was carried out as described in example 2. The resulting l,6-di-O-(4vmethylbenzyl)^>,4-O- isopropylidene-D-mannitol was not characterized but reacted according to the conditions described in example 4. Purification by flash chromatography provided 60% yield of the title compound. Η NMR (CDC1 3 ): 2.30 (s, 3H), 3.05 (s, IH), 3.60 (m. IH), 3.70 (m, 2H), 3.92 (s, IH), 4.52 (s, 2H), 4.56 (d, J = 1 1.0, IH), 4.70 (d, J = 11.0, IH), 7.1 1 (d, J = 7.5, 2H), 7.19 (d, J = 7.5, 2H), 7.30 (s, 5H). Example 49. Preparation of l,6-di-0-(4-trifluoromethyIbenzyl)-2,5-di-O-benzyl-D- mannitol (compound no. 27) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-trifluoromethylbenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4- trifluoromethylbenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 55% yield of the title compound. Η NMR (CDCI 3 ): 3.48 (s, IH), 3.68 (dd, J = 5.5, 11.0, IH), 3.75 (m, 2H), 4.00 (d, J = 7.0, IH), 4.60 (s, 2H), 4.61 (d, J = 9.0, IH), 4.72 (d, J = 10.0, IH), 7.30 (s, 5H), 7.41 (d, J = 7.5, 2H), 7.55 (d, J = 8.0, 2H). Example 50. Preparation of l,6-di-0-(4-cyanobenzyl)-2,5-di-O-benzyl-D-mannitol (compound no. 28) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-trifluoromethylbenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4- trifluoromethylbenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 55% yield of the title compound. Η NMR (CDC1 3 ): 2.90 (d, J - 5.5, IH), 3.70 (dd, J = 5.0, 10.5, IH), 3.75 (d, J = 3.5, 2H), 3.79 (m, 2H), 3.98 (t, J = 5.5, IH), 4.58 (s, 2H), 4.60 (d, J = 8, IH), 4.73 (d, J = 11.0, IH), 7.30 (s, 5H), 7.39 (d, 7.5. 2H), 7.57 (d, J = 7.5, 2H). Example 51. Preparation of l,6-di-0-(4-carbomethoxybenzyl)-2,5-di-O-benzyl-D- mannitol (compound no. 29) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-carbomefhoxybenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4- carbomethoxybenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 42% yield. Η NMR (CDCI 3 ): 2.98 (d, J = 5.6, IH), 3.69 (dd, J = 10.5, 5.1, IH), 3.77 (m, 2H). 3.90 (s, 3H), 3.98 (t, J = 5.7, IH), 4.58 (s, 2H), 4.62 (d, J = 11.9, IH), 4.73 (d, J = 12.5, IH), 7.30 (s, 5H), 7.37 (8.3, 2H), 7.98 (d, J = 8.6). Example 52. Preparation of l,6-di-O-(4-fluorobenzyl)-2,5-di-0-benzyl-D-mannitol (compound no. 31) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 52% yield. Η NMR (CDC1 3 ): 3.00 (d, J = 5.5, IH), 3.64 (dd, J = 9.2, 5.4, IH), 3.72 (m, 2H), 3.95 (t, J = 5.7, IH), 4.49 (s, 2H), 4.58 (d, J = 11.1, IH), 4.70 (d, J = 11.2, IH), 6.98 (t, J = 7.8, 2H), 7.30 (m, 7H). Example 53. Preparation of l,6-di-O-(2-fluorobenzyl)-2,5-di-0-benzyI-D-mannitol (compound no. 32) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 66% yield. Η NMR (CDCI 3 ): 1.2 (d, J = 7.4, IH), 3.63 (m. IH), 3.70 (m, 2H), 3.87 (d, J = 5.7, IH), 4.50 (s. 2H), 4.54 (d, J - 12.1, IH), 4.65 (d, J = 11.1, IH), 6.95 (t, J = 9.1, IH), 7.02 (t, J = 7.5, IH), 7.23. m. 6H), 7.31 (t, J = 7.4, IH). Example 54. Preparation of l,6-di-O-(2,4-fluorobenzyl)-2,5-di-0-benzyl-D-mannitoI (compound no. 33) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2,4-difluorobenzyl bromide was earned out as described in example 2. The resulting l,6-di-O-(2,4-difluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 49% yield. 'H NMR (CDC1 3 ): 3.00 (d, J = 5.5, IH), 3.68 (dd, J = 1 1.3, 5.9, IH), 3.72 (m, 2H), 3.95 (t, J = 6.4, IH), 4.49 (s, 2H), 4.56 (d, J = 11.6, IH), 4.70 (d, J = 11.2, IH), 6.81 (t, J = 5.3, 2H), 7.30 (m, 6H). Example 55. Preparation of l,6-di-0-(2-fluorobenzyl)-2,5-di-O-(4-bromobenzyl)-D- mannitol (compound no. 34) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzylbromide was carried out as described in example 2 by substituting benzylbromide with 2- fluorobenzylbromide. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol was not characterized but reacted with 4-bromobenzyl bromide using the conditions described in example 4. Purification by flash chromatography provided 60% yield of the title compound, mp. 107°C. 'H NMR (CDCI 3 ): 3.00 (d, J = 5.81H), 3.68 - 3.70 (m, IH), 3.77 - 3.93 (m, 2H), 3.92 (d, J = 5.8. IH), 4.53 (d, J = 1 1.7, IH), 4.62 (d, J = 11.7, IH), 4.60 (s, 2H), 7.00 - 7.42 (m, 8H). Example 56. Preparation of l,6-di-O-(2-fluorobenzyι)-2,5-di-O-(4-methoxybenzyl)-D- mannitol (compound no. 36) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzylbromide was earned out as described in example 2 by substituting benzylbromide with 2- fluorobenzylbromide. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol was not characterized but reacted with 4-methoxybenzyl bromide in the conditions described in example 4. Purification by flash chromatography provided 72%> yield of the title compound. Η NMR (CDC1 3 ): 3.00 (d, J = 5.5, IH), 3.67 (m, IH), 3.73 (m, IH), 3.78 (s, 3H), 3.92 (t, J = 5.5, IH), 4.50 (d, J = 1 1.0, IH), 4.60 (s, 2H), 4.66 (d, J = 11.0, IH), 6.83 (d, J = 9.0, 2H), 7.03 (t, J = 9.0, IH), 7.10 (t, J = 7.5, IH), 7.22 (d, J = 7.5, 2H), 7.27 (m, IH), 7.39 (t, J = 7.5, IH). Example 57. Preparation of l,6-di-0-(2-fluorobenzyl)-2,5-di-O-(4-methyIthiobenzyl)- D-mannitol (compound no. 68) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with bromide according to the conditions described in example 4. Purification by flash chromatography provided a 15% yield. 'H NMR (CDClj): 2.45 (s. 3H). 3.00 (d. J = 5.3, IH). 3.69 - 3.78 (m. 3H). 3.93 (s. 1), 4.54 (d. J = 1 1.5. 1H). 4.61 (d. J = 3.0. 2H). 4.67 (d, J = 1 1.5. IH). 7.03 (t, J = 7.5. IH). 7.10 (t, J = 7.5. IH). 7.18 - 7.29 (m. 5H). 7.38 (t. J = 7.0, IH). Example 58. Preparation of l,6-di-0-(4-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)- D-mannitol (compound no. 58) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-benzyloxybenzyl chloride was carried out as described in example 2 by substituting benzylbromide with 4- benzyloxybenzylchloride. The resulting l ,6-di-O-(4-benzyloxybenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide in the conditions described in example 4. Η NMR (CDCI 3 ): 3.04 (d, J = 5.5, IH), 3.62 (dd, J = 3.5, 9.0, IH), 3.69 (d, J = 3.5. IH), 3.71 (m. 3H), 3.92 (t. J = 6.0. IH), 4.46 (s. 2H), 4.53 (d, J = 1 1.0. IH), 4.64 (d, J = 1 1.0, ) IH). 5.04 (s. IH). 6.90 - 7.00 (m, 4H), 7.21 - 7.27 (m, 4H). 7.31 (t, J = 7.5, IH), 7.37 (t. J = 7.5. 2H), 7.41 (d, J = 7.5. 2H). Example 59. Preparation of l,6-di-O-(2-methylbenzyl)-2,5-di-O-(4-fluorobenzyl)-D- mannitol (compound no. 37) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-methylbenzyl chloride was carried out as described in example 2 by substituting benzyl bromide with 2-methylbenzyl chloride. The resulting l,6-di-O-(2-methylbenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide in the conditions described in example 4. Purification by flash chromatography provided 71 % yield of the title compound. 'H NMR (CDC1 3 ): 2.30 (s, 3H), 3.02 (d, J = 5.5, IH), 3.65 (m, IH), 3.73 (m, 2H), 3.93 (t, J = 5.5, IH), 4.53 (s, 2H), 4.55 (d, J = 1 1, IH), 4.70 (d, J = 1 1, IH), 6.90 - 7.30 (m, 8H). Example 60. Preparation of l,6-di-O-(2-fluorobenzyl)-2,5-di-0-(2-methylbenzyl)-D- mannitol (compound no. 38) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2 by substituting benzyl bromide with 2-fluorobenzyl bromide. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with 2-methylbenzyl bromide in the conditions described in example 4. Purification by flash chromatography provided 61%) yield of the title compound. 'H NMR (CDCI 3 ): 2.30 (s, 3H), 2.96 (d, J = 6.5, IH), 3.69 (dd, J = 4.5, 8.5, IH), 3.77 (m, 2H), 3.92 (t, J = 6.0, IH), 4.53 (d, J = 1 1.5, IH), 4.60 (s, 2H), 4.73 (d, J = 11.0, IH), 7.03 (t, J = 8, IH), 7.06 - 7.25 (m, 6H), 7.38 (t, J = 8, IH). Example 61. Preparation of l,6-di-0-(2-fluorobenzyl)-2,5-di-O-(4-methylbenzyl)-D- mannitol (compound no. 56) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2 by substituting benzyl bromide with 2-fluorobenzyl bromide. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with 4-methylbenzyl bromide in the conditions described in example 4. Purification by flash chromatography provided 61% yield of the title compound. 'H NMR (CDC1 3 ): 2.33 (s, 3H), 3.00 (d, J = 5.5, IH), 3.63 (dd, J = 4.0, 9.5, IH), 3.72 (m, 2H), 3.77 (d, J = 4.0, IH), 3.92 (t, J = 4.0, IH), 4.53 (d, J = 1 1.0, IH), 4.58 (d, 2H), 4.68 (d, J = 11.5, IH), 7.02 (t, J = 9.0, IH), 7.10 (m, 3H), 7.19 (d, J = 7.5, 2H), 7.25 (dd, J = 7.5, 7.0, IH), 7.39 (t, J = 7.5, IH). Example 62. Preparation of l,6-di-O-(2,6-difluorobenzyl)-2,5-di-O-(4-fluorobenzyl)- D-mannitol (compound no. 39) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2,6-difluorobenzyl chloride was caπied out as described in example 2 by substituting benzyl bromide with 2,6- difluorobenzylchloride. The resulting l,6-di-O-(2,6-difluorobenzyl)-3.4-O-isopropylidene- D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide using the conditions described in example 4. Purification by flash chromatography provided 68%> yield of the title compound, mp. 110°C. •H NMR (CDCI 3 ): 2.92 (d, J = 7.0, IH), 3.65-3.71 (m, 2H), 3.70 (dd, J = 9.5, 3.5. IH), 3.85 (t, J = 6.5, lH), 4.53 (d, J = 11.0. 1H), 4.61 (d, J = 1 1.0, IH), 4.63 (s, 2H), 6.89 (t, J = 8.0, 2H), 6.97 (t, J = 9.0. 2H), 7.26 (m, 3H). Example 63. Preparation of l,6-di-0-(2-fluorobenzyl)-2,5-di-O-(4-fluorobenzyI)-D- mannitol (compound no. 40) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2 by substituting benzyl bromide with 2-fluorobenzyl bromide. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide in the conditions described in example 6 substituting the 4-cyanobenzylbromide with 4-fluorobenzyl bromide. Purification by flash chromatography provided 60%> yield of the title compound, mp. 71°C. Η NMR (CDCI 3 ): 3.00 (s, IH), 3.68 (m, IH), 3.78 (m, 2H), 3.92 (s, IH), 4.54 (d, J = 1 1.3, IH), 4.60 (s, 2H), 4.67 (d, J = 11.4, IH), 6.97 (m, 2H), 7.03 (t, J = 9.2, IH), 7.09 (t, J = 7.5, IH), 7.26 (m, 2H), 7.37 (t, J = 7.4, IH). Example 64. Preparation of l,6-di-0-(4-bromobenzyl)-2,5-di-O-benzyl-D-mannitol (compound no. 54) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2 by substituting benzyl bromide with 4-bromobenzyl bromide. The resulting l,6-di-O-(4-bromobenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide in the conditions described in example 4 substituting the 4-cyanobenzylbromide with benzyl bromide. Purification by flash chromatography provided 56% yield of the title compound. Η NMR (CDC1 3 ): 3.00 (br, IH), 3.67 (dd, J = 5.5, 11.0, IH), 3.73 (d. J = 3.5, IH), 3.72 (m, 2H), 3.97 (d, J = 5.5, IH), 4.50 (s, 2H), 4.60 (d, J = 1 1.5, IH), 4.73 (d, J = 11.5. IH), 7.19 (d, J = 7.5. 2H), 7.32 (s, 5H), 7.45 (d, J = 7.0, 2H). Example 65. Preparation of l,6-di-0-(4-chlorobenzyl)-2,5-di-O-benzyI-D-mannitol (compound no. 55) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-chlorobenzyl chloride was caπied out as described in example 2 by substituting benzyl bromide with 4-chlorobenzyl chloride. The resulting l,6-di-O-(4-chlorobenzyl)-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with 4-chlorobenzyl bromide in the conditions described in example 4 substituting the 4-cyanobenzylbromide with benzyl bromide. Purification by flash chromatography provided 62% yield of the title compound. Η NMR (CDC1 3 ): 2.97 (br, IH), 3.65 (dd, J = 5.5, 1 1.0, IH), 3.70 (d, J = 3.5, IH), 3.72 (m, 2H), 3.95 (d, J = 5.5, IH), 4.49 (s, 2H), 4.58 (d, J = 12.0, IH), 4.71 (d, J = 12.0, IH), 7.30 (m, 9H). Example 66. Preparation of l,6-di-0-(4-carboxybenzyl)-2,5-di-O-benzyI-D-mannitol (compound no. 51) The base hydrolysis of l,6-di-O-(4-cyanobenzyl)-2,5-di-O-benzyl-D-mannitol prepared in example 50 was caπied out as in example 45, affording the title compound in 41% yield. Η NMR (CDC1 3 ): 3.70 (m, 3H), 3.90 (s, 2H), 4.00 (d, J = 5.5, IH), 4.58 (s, 3H), 4.71 (d, J = 11.2, IH), 7.30 (m, 7H), 8.02 (d, J = 7.6, 2H), Example 67. Preparation of l,6-di-0-cyclopropylmethyl-2,5-di-O-dibenzyl-D- mannitol (compound no. 89) The alkylation of 3,4-O-isopropylidene-D-mannitol with cyclopropylmethyl bromide was caπied out as described in example 2 by substituting benzyl bromide with cyclopropylmethyl bromide. The resulting l,6-di-O-cyclopropylmethyl-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide in the conditions described in example 4. Purification by flash chromatography provided a 38%> yield of the title compound. 'H NMR (CDCI 3 ): 0.19 (d, J = 4.8, 2H), 0.52 (d, J = 7.5, 2H), 1.04 (m, IH), 3.22 (d, J = 5.8, IH), 3.31 (t, J = 5.1, 2H), 3.65 (m, IH), 3.74 (m, 2H), 3.94 (t, J = 5.6, IH), 4.63 (d, J = 11.4, IH), 4.74 (d, J = 11.6, IH), 7.30 (s, 5H). Example 68. Preparation of l,6-di-O-allyl-2,5-di-O-benzyI-D-mannitol (compound no. 90) The alkylation of 3,4-O-isopropylidene-D-mannitol with allyl bromide was carried out as described in example 2 by substituting benzyl bromide with allyl bromide. The resulting l,6-di-O-cyclopropylmethyl-3,4-O-isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide in the conditions described in example 4. Purification by flash chromatography provided a 50% yield of the title compound. 'H NMR (CDC1 3 ): 3.06 (d, J = 6.0, IH), 3.63 (dd, J = 9.6, 4.8. 5, IH), 3.72 (m, 2H), 3.93 (t, J = 5.7, IH), 4.01 (d, J = 5.4, 2H), 4.60 (d, J = 11.3, IH), 4.74 (d, J = 11.4, IH), 5.17 (d, J = 10.5, IH), 5.27 (d, J = 17.4, IH), 5.90 (m, IH), 7.30 (s. 5H). Example 69. Preparation of l,6-di-O-(4-hydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D- mannitol (compound no. 4) Following the indications of step B of example 8, the product from example 58 was hydrogenolyzed to the title compound (37%) and to a smaller yield (12%)) of l-O-(4- hydroxybenzyl)-6-O-(4-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol. l-O-(4-hydroxybenzyl)-6-O-(4-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 76) Η NMR (CDCI 3 ): 3.23 (d, J = 5.5, IH), 3.26 (d, J = 5.5, IH), 3.64 - 3.67 (m, 2H), 3.68 - 3.76 (m, 4H), 3.96 - 3.98 (m, 2H), 4.45 (s, 2H), 4.48 (s, 2H), 4.54 (d, J = 11.5, 2H), 4.66 (d, J = 11.5, 2H), 6.73 (d. J = 7.0, 2H), 6.90 - 7.00 (m, 6H), 7.10 (d, J = 8.8, 2H), 7.20 - 7.45 (m, 11H). 1.6-di-O-(4-hydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannito Η NMR (CDCI 3 ): 3.34 (d. J = 5.5, IH), 3.62 (m. IH), 3.72 (m, 2H), 3.92 (t, J = 5.5, IH), 4.46 (s. 2H), 4.52 (d, J = 11.0, IH), 4.63 (d, J = 11.0, IH), 5.04 (s, 2H), 6.92 - 7.00 (m, 4H), 7.2 - 7.50 (m, 9H). Example 70. Preparation of l,2,6-tri-O-benzyI-5-O-(4-fluorobenzyl)-D-mannitol (compound no. 8) Step A. l,6-di-O-benzyl-2-O-(4-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol To a solution of l,6-di-O-benzyl-3,4-O-isopropylidene-D-mannitol (402 mg, 1 mmol), obtained as in example 2, in toluene (10 mL) was added silver oxide (348 mg, 1.5 mmol) and 4-fluorobenzyl bromide (1.2 g, 0.63 mmol). The mixture was stiπed at room temperature for 15h. The mixture was then filtered and the filtrate was concentrated to dryness to afford the cmde product that was purified by flash chromatography eluting with 70%) EtOAc in hexane. Η NMR (CDCI 3 ): 1.33 (s, 3H), 1.35 (s, 3H), 3.10 (d, J = 3.5, IH), 3.55 (dd, J = 9.5, 5.5, IH), 3.62 - 3.82 (m, 3H), 3.69 - 3.72 (m , IH), 3.82 (d, J = 12.0, IH), 3.96 (t, J = 7.5, IH), 4.09 (t, J = 7.5, IH), 4.54 (s, 2H), 4.55 (s, 2H), 4.60 (d, J = 12.0, IH), 4.75 (d, J = 12.0, IH), 6.94 (dd, J = 9.5, 7.0. 2H), 7.27 (dd, J = 8.5, 6.0, 2H), 7.30 - 7.34 (m, 10H). Step B. l,2,6-tri-O-benzyl-5-O-(4-fluorobenzyl)-D-mannitol The product thus purified was then subjected to a further alkylation with benzyl brortfide under conditions described in example 3 to provide the title compound in a 71% yield. Η NMR (CDC1 3 ): 3.00 (d, J = 5.5, 2H), 3.65 (m, 2H), 3.75 (m, 4H), 3.96 (dd, J = 6.5, 1 1.5, 2H), 4.49 (s, 2H), 4.53 (s, 2H), 4.58 (d, J = 10.5, 2H), 4.70 (d, J = 11.5, IH), 4.72 (d, J = 1 1.5, IH), 6.90 (t, J = 7, 2H), 7.30 (17H). Example 71. Preparation of 1,2,6-tri-O-benzyI-D-mannitol (compound no. 98) Following the indications outlined in step A of example 70 but substituting 4-fluorobenzyl bromide with benzyl bromide. The cmde intermediate, l,2,6-tri-O-benzyl-3,4-O- isopropylidene-D-mannitol, was treated with 5%> HCl methanolic solution, to yield the title compound in 89%> yield after flash chromatography. l,2,6-tri-O-benzyl-3,4-O-isopropylidene-D-mannitol 'H NMR (CDC1 3 ): 1.34 (s, 3H), 1.39 (s, 3H), 2.29 (t, J = 7.0, IH), 3.58 - 3.6 (m, 2H), 3.70 - 3.81 (m, 4H), 4.13 (m, IH), 4.23 (m, IH), 4.57 (s, 2H), 4.56 - 4.60 (m, 3H), 4.77 (d, J = 11.2, IH), 7.22 - 7.38 (m, 15H). 1 ,2,6-tri-O-benzyl-D-mannitol 'H NMR (CDC1 3 ): 2.40 (dd, J = 7.5, 4, IH), 3.00 (d, J = 7.5, IH), 3.07 (d, J = 4, IH), 3.58 (m, IH), 3.68 (m, 2H), 3.80 (m, 3H), 3.94 (dd, J = 13, 7, IH), 4.54 (s, 2H), 4.57 (d, J = 12.0, IH), 4.59 (d. J = 11.0, IH), 4.62 (d, J - 11.0, IH), 4.72 (d, J = 11.0, IH), 732 (m, 15H). Example 72. Preparation of l,2,6-tri-O-benzyl-5-0-(4-aminobenzyl)-D-mannitol (compound no. 9) A solution of l,2,6-tri-O-benzyl-5-O-(4-nitrobenzyl)-D-mannitol (59 mg, 0.1 mmol), obtained as in example 103 in MeOH (5 mL) was hydrogenated at atmospheric pressure using 5%> Pd/C for 1 h. The catalyst was removed by filtration and the filtrate was evaporated to dryness to afford 75% of the title compound. Η NMR (CDC1 3 ): 3.00 (d, J = 5.5, IH), 3.65 (m, 2H), 3.75 (m, 4H), 3.96 (t, J = 6.0, 2H), 4.49 (s, 2H), 4.53 (s, 2H), 4.58 (d, J = 11.0, 2H), 4.70 (d, J = 11.4, IH), 4.73 (d, J = 11.2, IH), 7.00 (m, 2H), 7.30 (m, 17H). Example 73. Preparation of l,2,5-tri-0-benzyl-6-O-(2-fluorobenzyl)-D-mannitol (compound no. 10) Following the indications of example 2, but carrying out the reaction with 2-fluorobenzyl chloride at room temperature instead of 60°C, the monoalkylated mannitol derivative was isolated and further alkylated with benzyl bromide (4 eq.) using the conditions described in example 3. Purification by flash chromatography eluting with 30% EtOAc in hexane provided 89% of the desired product. Η NMR (CDCI 3 ): 3.03 (t. J = 8.5, 2H), 3.65 - 3.79 (m, 6H), 3.9fr(d, J = 11.0, 2ft), 4.54 (s, 2H), 4.62 (m, 4H), 4.71 (d, J = 12.5, IH), 4.73 (d, J = 12.5, IH), 7.02 (t, J = 9.5, IH), 7.09 (t, J = 7.5, IH), 7.30 (m. 16H), 7.39 (t, J = 7.5, IH). Example 74. Preparation of l,6-di-0-benzyl-2-O-(4-nitrobenzyl)-D-mannitol (compound no. 99) and of l,6-di-0-benzyl-2,5-di-O-(4-nitrobenzyl)-D-mannitoI (compound no.13) To a solution of l,6-di-O-benzyl-3,4-O-isopropylidene-D-mannitol, obtained as in example 2, (402 mg, 1 mmol) in toluene (10 mL) was added freshly prepared silver oxide (464 mg, 2 mmol) and 4-nitrobenzylbromide (648 mg, 3 mmol). The suspension was stiπed at room temperature overnight. More silver oxide (464 mg, 2 mmol) was added and the reaction was refluxed for 24 h. The insoluble material was filtered off and the filtrate was concentrated in vacuo. The residue was taken up in 5% HCl methanolic solution (6 mL). After 5 h of stiπing at room temperature, the solvent was evaporated in vacuo and the cmde was purified by chromatography eluting with 50%> EtOAc in hexane to yield 60% of 1 ,6-di-O-benzyl-2-O-(4-nitrobenzyl)-D-mannitol and 12 % of 1,6-di-O- benzyl-2,5-di-O-(4-nitrobenzyl)-D-mannitol. 1 ,6-di-O-benzyl-2-O-(4-nitrobenzyl)-D-mannitol Η NMR (CDCI 3 ): 3.14 (d, J = 7.0, IH), 3.20 (d, J = 7.0, IH), 3.49 (d, J = 6.0, IH), 3.60 (dd, J = 5.5, 9.0, IH), 3.69 (m. 2H), 3.77 (m, 2H), 3.82 (t, J = 7.0, IH), 3.90 (m, IH), 4.02 (t, J = 6.0, IH), 4.09 (d, J = 7.0, IH), 4.1 1 (d, J = 7.0, IH), 7.35 (m, 10H), 7.40 (d, J = 8.0, IH), 8.10 (d, J = 8.0, IH). l,6-di-O-benzyl-2,5-di-O-(4-nitrobenzyl)-D-mannitol Η NMR (CDC1 3 ): 3.04 (d, J = 5.5, IH), 3.70 (m, IH), 3.78 (m, IH), 4.00 (t, J = 5.5, IH), 4.53 (s, 2H), 4.70 (d, J = 1 1.0, IH), 4.82 (d, J = 1 1.0, IH), 7.30 (m, 5H), 7.43 (d, J - 8.5, 2H), 8.14 (d, J = 8.5, 2H). Example 75. Preparation of l,6-di-(4-hydroxymethylbenzyl)-2,5-dibenzyl-D- mannitol (compound no. 48) In a similar fashion as described in example 44, 2,5-di-O-benzyl-l,6-di-O-(4- carbomethoxybenzyl)-D-mannitol was reduced to the desired product with lithium aluminium hydride in 83% yield. Η NMR (CDCI 3 ): 3.02 (d, J = 6.6, IH), 3.65 (dd, J = 3.6, 9.2, IH), 3.74 (m, 3H), 3.96 (t, J = 5.5, IH), 4.53 (s, 2H), 4.60 (d, J = 11.5, IH), 4.66 (s, 2H), 4.71 (d, J = 12.0, IH), 7.30 (m, 9H). Example 76. Preparation of l,6-di-0-benzyl-2,5-di-O-(3-hydroxybenzyl)-D-mannitol (compound no. 3) As described in the example 4, the title compound was prepared by reacting 1 ,6-di-O- benzyl-3,4-O-isopropylidene-D-mannitol with 3-benzyloxybenzyl bromide. The resulting intermediate, 1 ,6-di-O-benzyl-2,5-di-O-(3-benzyloxybenzyl)-D-mannitol, was hydrogenated under the conditions described in example 16. After purification by flash chromatography, the title compound was obtained in 83% yield. Η NMR (CDC1 3 ): 3.30 (d, J = 5.5, IH), 3.69 (dd, J = 11.0, 5.5, IH), 3.75 (m, 2H), 4.45 (d, J = 11.0, IH), 4.53 (s, 2H), 4.65 (d, J = 11.0, IH), 6.19 (s, IH), 6.70 - 7.30 (m, 9H). Example 77. Preparation of l,6-di-0-(2-fluorobenzyl)-2,5-di-O-(4-benzyloxybenzyl)- D-mannitol (compound no. 7) l ,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol obtained using a similar procedure as described for example 2, was treated with 4-benzyloxybenzyl bromide according to example 4, the title compound was obtained in 51 %> yield. 'H NMR (CDC1 3 ): 3.00 (d, J = 6.0, IH), 3.67 (dd, J = 5.5, 9.5, IH), 3.76 (m, 2H), 3.92 (t, J = 5.5, IH), 4.51 (d, J = 11.0, IH), 4.60 (d, J - 3.5, 2H), 4.63 (d, J = 12.0, IH), 5.04 (s, 2H), 6.89 (d, J = 7.5, 2H), 7.01 (t, J = 9.0, IH), 7.08 (t, J = 7.5, IH), 7.22 (d, J = 7.5, 2H), 7.28 - 7.41 (m, 7H). Example 78. Preparation of l,6-di-O-(2-fluorobenzyl)-2,5-di-O-(4-hydroxybenzyl)-D- mannitol (compound no. 5) As described in the example 16 and substituting l,6-di-O-benzyl-2,5-di-O-(4- benzyloxybenzyl)-D-mannitol with 1 ,6-di-O-(2-fluorobenzyl)-2,5-di-O-(4- benzyloxybenzyl)-D-mannitol (example 77), careful hydrogenation afforded the^title compound in 85%) yield. 'H NMR (CDC1 3 ): 3.41 (d, J = 5.5, IH), 3.67 (dd, J = 11.0, 6.0, IH), 3.74 (d, J = 8.0, 2H), 3.98 (t, J = 5.5, IH), 4.42 (d, J = 11.0, IH), 4.59 (s, 2H), 4.61 (d, J = 11.0, IH), 6.31 (s, IH), 6.62 (d, J = 9.5, 2H), 7.00 - 7.40 (m, 6H). Example 79. Preparation of l,6-di-O-(4-fluorobenzyl)-2,5-di-O-(3,4- dihydroxybenzyl)-D-mannitol (compound no. 69) Step A. 1 ,6-di-O-(4-fluorobenzyl)-2,5-di-O-(3,4-dibenzyloxybenzyl)-D-mannitol (compound no 75) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with 3,4-dibenzyloxybenzyl chloride according to the conditions described in example 4. Purification by flash chromatography provided a 8% yield of the title compound. Η NMR (CDCI 3 ): 3.02 (s, 2H), 3.62 - 3.59 (m, 2H), 3.67 - 3.74 (m, 4H), 3.92 (d, J = 6.5, 2H), 4.44 (s, 4H), 4.53 (d, J = 11.5, 2H), 4.65 (d, J = 1 1.5, 2H), 5.11 (s, 2H), 5.15 (s, 2H), 6.82 (d, J = 8.0, 2H), 6.89 (d, J = 9.0, 2H), 6.95 - 6.99 (m, 6H), 7.24 - 7.38 (m, 17H), 7.42 - 7.45 (m, 7H). Step B. 1 ,6-di-O-(4-fluorobenzyl)-2,5-di-O-(3,4-dihydroxybenzyf)-D-mannitol Hydrogeno lysis of the product of step A of this example according to the conditions of step B of the example 8, the title compound was obtained in 47%> yield. 'H NMR (CDC1 3 ): 3.00 (s, 2H), 3.59 (t, J = 5.5, 2H), 3.66 (m, 6H), 4.25 (d, J = 11.5, 2H), 4.42 (d, J = 1 1.0, 2H), 6.54 (d, J = 8.0, 2H), 6.61 (d, J = 8.0, 2H), 6.72 (s, 2H), 6.76 (s, 2H), 6.93 (t, J = 7.5, 6H), 7.19 (t, J = 6.5, 4H). Example 80. Preparation of l,6-di-0-(4-fluorobenzyI)-2,5-0-(3,5-dihydroxybenzyI)- D-mannitol (compound no. 70) Step A. l,6-di-O-(4-fluorobenzyl)-2,5-O-(3,5-dibenzyloxybenzyl)-D-mannitol (compound no. 73) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-fluorobenzyl bromide was caπied out as described in example 2. The resulting l,6-di-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with 3,5-dibenzyloxybenzyl chloride according to the conditions described in example 4. Purification by flash chromatography provided a 26%) yield of the title compound. 'H NMR (CDCI 3 ): 2.98 (s, IH), 3.68 - 3.78 (m, 3H), 3.95 (s, IH), 4.54 - 4.66 (m, 4H), 4.97 (s, 4H), 6.52 - 6.58 (m, 3H), 6.97 - 7.07 (m, 2H), 7.20 - 7.38 (m, 12H). Step B. 1 ,6-di-O-(4-fluorobenzyl)-2,5-O-(3,5-dihydroxybenzyl)-D-mannitol Hydrogenolysis of the product of step A of this example according to the conditions of step B of the example 8, the title compound was obtained in 57% yield. 'H NMR (CDC1 3 ): 3.67 - 3.77 (m, 6H), 3.89 (d, J = 9.9, 2H), 3.98 (d, J = 6.8, 2H), 4.48 - 4.57 (m, 6H), 4.65 (d, J = 1 1.8, 2H), 6.28 (s, 2H), 6.38 (s, 2H), 7.06 (t, J = 8.4, 4H), 7.39 (t, J = 6.1, 4H), 8.14 (s, 4H). Example 81. Preparation of l,6-di-O-(4-tert-butylbenzyl-2,5-di-O-(4-fluorobenzyl)-D- mannitol (compound no. 42) The alkylation of 3,4-O-isopropylidene-D-mannitol with 4-tert-butylbenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(4-tert-butylbenzyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 32% yield of the title compound. Η NMR (CDCI 3 ): 1.31 (s, 9H), 3.05 (d, J = 4.5, IH), 3.73 (s, IH), 3.75 (s, IH), 3.94 (s, IH), 4.51 (s, 2H), 4.55 (d, J = 11.5, IH), 4.67 (d, J - 1 1.0, IH), 6.97 (t, J = 8, 2H), 7.25 (s, 4H), 7.35 (d, J = 7.0, 2H). Example 82. Preparation of l,6-di-O-(2-thienylmethyl)-2,5-di-O-benzyl-D-mannitol (compound no. 92) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-thienylmethyl bromide was caπied out as described in example 2. The resulting l,6-di-O-(2-thienylmethyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 40% yield of the title compound. 'H NMR (CDC1 3 ): 2.95 (d, J = 6.0, IH), 3.65 (m, IH), 3.71 (m, 2H), 3.92 (m, IH), 4.56 (d, J = 11.5, IH), 4.68 (s, 2H), 4.71 (d, J = 11.2, IH), 6.95 (m, 2H), 7.25 (m, IH), 7.30 (s, 5H). Example 83. Preparation of l,6-di-O-(2-thienylmethyl)-2,5-di-O-(4-fluorobenzyl)-D- mannitol (compound no. 93) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-thienylmethyl bromide was caπied out as described in example 2. The resulting l,6-di-O-(2-thienylmethyl)-3,4-O- isopropylidene-D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 42% yield of the title compound. Η NMR (CDCI 3 ): 2.94 (d, J = 3.1, IH), 3.64 (m, IH), 3.71 (m, 2H), 3.89 (s, IH), 4.53 (d, J = 11.2, IH), 4.68 (d, J = 11.2, IH), 4.70 (s, 2H), 7.00 (m, 4H), 7.26 (m, 3H). Example 84. Preparation of l,6-di-0-cinnamyl-2,5-di-O-benzyl-D-mannitol (compound no. 94) The alkylation of 3,4-O-isopropylidene-D-mannitol with cinnamyl bromide was carried out as described in example 2. The resulting l,6-di-O-cinnamyl-3,4-O-isopropylidene-D- mannitol was not characterized but reacted with benzyl bromide according to the conditions described in example 4. Purification by flash chromatography provided a 37%) yield of the title compound. Η NMR (CDC1 3 ): 3.07 (d, J = 6.0, IH), 3.68 (dd, J = 6.0, 11.0, IH). 3.76 (m, 2H), 3.98 (t, J = 5.5, IH), 4.26 (dd, J = 12.4, 5.8, IH), 4.35 (dd, J = 12.5, 5.9, IH), 4.56 (s, 2H), 6.27 (m, IH), 6.58 (d, J = 15.7, IH), 7.21 - 7.36 (m, 10H). Example 85. Preparation of l,6-di-O-(3-phenyl-l-propyI)-2-0-(4-fluorobenzyl)-D- mannitol (compound no. 100) Step A. l,6-di-O-(3-phenyl-l-propyl)-3,4-O-isopropylidene-D-mannitol The alkylation of 3,4-O-isopropylidene-D-mannitol with cinnamyl bromide was carried out as described in example 2. The resulting l,6-di-O-cinnamyl-3,4-O-isopropylidene-D- mannitol was not characterized but hydrogenated using 5% palladium on charcoal in a methanolic solution at one atmosphere of hydrogen. Filtration and evaporation of the filtrate to dryness afforded the intermediate. Η NMR (CDCI 3 ): 1.37 (s, 6H), 1.73 (q, J = 7.0, 4H), 2.70 (t, J = 7.5, 4H), 3.48 - 3.55 (m, 6H), 3.68 - 3.70 (m, 2H), 3.78 (s, 2H), 3.89 - 3.91 (m, 2H), 7.17 - 7.20 (m, 5H), 7.26 - 7.29 (m, 5H). Step B. l,6-di-O-(3-phenyl-l-propyl)-2,5-di-O-(4-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol l,6-Di-O-(3-phenyl-l-propyl)-3,4-O-isopropylidene-D-mannitol (90 mg, 0.20 mmol) was alkylated with 4-fluorobenzyl bromide as described in example 3. Purification by flash chromatography eluting with 30% EtOAc in hexane afforded the monoalkylated product (49%) and the dialkylated product (43%). 1 ,6-di-O-(3 -phenyl- 1 -propyl)-2-O-(4-fluorobenzyl)-3 ,4-O-isopropylidene-D-mannitol 'H NMR (CDCI 3 ): 1.36 (s, 6H), 1.91 (q, J = 6.5, 4H), 2.68 (q, J = 8.0, 4H), 3.60 - 3.78 (m, 6H), 3.95 (t, J = 7.0, IH), 4.08 (t, J = 7.0, IH), 4.66 (d, J = 10.0, IH), 4.79 (d, J = 11.5, IH), 7.00 (t, J = 8.5, 2H), 7.17 - 7.18 (m, 6H), 7.25 - 7.28 (m, 4H), 7.33 - 7.34 (m, 2H). l,6-di-O-(3-phenyl-l-propyl)-2,5-di-O-(4-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol 'H NMR (CDCI 3 ): 1.37 (s, 6H), 1.87 (q, J = 6.0, 4H), 2.66 (t, J = 7.5, 4H), 3.40 (t, J = 5.5, 4H), 3.52 - 3.55 (m, 2H), 3.66 - 3.69 (m, 4H), 4.11 - 4.13 (m, 2H), 4.55 (d, J = 11.5, 2H), 4.71 (d, J = 11.5, 2H), 6.93 - 7.00 (m, 4H), 7.15 - 7.27 (m, 14H). Step C. l,6-di-O-(3-phenyl-l-propyl)-2-O-(4-fluorobenzyl)-D-mannitol The monoalkylated product obtained in step A of this example was treated with p- toluenesulfonic acid in MeOH at room temperature for 18 h. Evaporation of the volatiles in vacuo afforded a residue that was purified by flash chromatography, eluting with 30% EtOAc in hexane, yielding the title compound (73%>). Η NMR (CDC1 3 ): 1.90 (q, J = 6.0, 4H), 2.66 (m, 4H), 3.05 (d, J = 5.5, IH), 3.30 (s, IH), 3.48 - 3.54 (m, 4H), 3.55 - 3.61 (m, IH), 3.62 - 3.68 (m, 3H), 3.74 (m, 2H), 3.85 (s, IH), 3.99 (s, IH), 4.61 (d, J = 11.5, IH), 4.69 (d, J = 11.5, IH), 7.00 (d, J = 8.0, 2H), 7.16 - 7.19 (m, 6H), 7.25 - 7.31 (m, 6H). Example 86. Preparation of l,6-di-0-(3-phenyI-l-propyl)-2,5-di-O-(4-fluorobenzyl)- D-mannitol (compound no. 95) l,6-Di-O-(3-phenyl-l-propyl)-3,4-O-isopropylidene-D-mannitol prepared in step A of example 85 was reacted as in step C of example 85 using ^-toluenesulfonic acid in methanol to achieve the removal of the ketal. Purification by flash chromatography eluting with 30% EtOAc in hexane provided 57%> of the title compound. •H NMR (CDCI 3 ): 1.90 (s, 4H), 2.67 (s, 4H), 3.13 (s, 2H), 3.46 - 3.47 (m, 4H), 3.68 (s, 2H), 3.68 - 3.72 (m, 4H), 3.92 (s, 2H), 4.58 (d, J = 11.0, 2H), 4.70 (d, J = 11.0, 2H), 6.99 - 7.01 (m, 4H), 7.16 - 7.17 (m, 6H), 7.25 - 7.29 (m, 8H). Example 87. Preparation of l,6-di-O-benzyl-2-O-(4-fluorobenzyI)-5-O-(2- thienylmethyl)-D-mannitol (compound no. 96) Step A. l,6-di-O-benzyl-2-O-(4-fluorobenzyl)-3.4-O-isopropylidene-D-mannitol To a solution of l,6-di-O-benzyl-3,4-O-isopropylidene-D-mannitol (402 mg, 1 mmol), obtained as in example 2, in toluene (10 mL) was added silver oxide (348 mg, 1.5 mmol) and 4-fluorobenzyl bromide (375 mg, 1.2 mmol). The mixture was stiπed at room temperature for 15 h. The insoluble material was filtered off and the filtrate was evaporated to dryness affording crude l,6-di-O-benzyl-2-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol. The compound was purified by flash chromatography using 30% EtOAc in hexane to yield 93 %> of desired product. Step B. 1 ,6-di-O-benzyl-2-O-(4-fluorobenzyl)-5-O-(2-thienylmethyl)-D-mannitol Sodium hydride (9.6 mg, 0.4 mmol) was added in portions to a solution of 1,6-di-O- benzyl-2-O-(4-fluorobenzyl)-5-O-(2-thienylmethyl)-D-mannitol (100 mg, 0.20 mmol) in DMF (3 mL). After stiπing for a period of 10 minutes, 2-thienylmethyl chloride (264 mg, 0.2 mmol) in DMF (1 mL) was added dropwise and the reaction mixture was stiπed at room temperature for 3 h. IN HCl was then added and the resulting mixture was extracted twice with EtOAc. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The residue was taken up in 5%> HCl in MeOH and the reaction was stiπed at room temperature for 5 h. Water was added and the reaction mixture was extracted with EtOAc. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The resulting residue was purified by flash chromatography using 30% EtOAc in heftane to provide the title compound in 72% yield. 'H NMR (CDC1 3 ): 2.90 (d, J = 5.5, IH), 2.96 (d, J = 5.5, IH), 3.65 (dd, J = 10.5. 5.5, 2H), 3.75 (m, 4H), 3.90 (m, 2H), 4.55 (d, J = 1 1.0, IH), 4.61 (s, 4H), 4.68 (d, J = 11.0. IH), 4.77 (d, J = 13.0, IH), 4.91 (d. J = 12.5, IH), 6.97 (m, 3H), 7.03 (t, J = 9.0, 2H), 7.10 (t, J = 7.5, 2H), 7.27 (m, 5H), 7.39 (t, J = 7.5, 2H). Example 88. Preparation of l,6-di-O-(2-fluorobenzyl)-2-O-(4-fluorobenzyl)-5-O-(2- thienylmethyI)-D-mannitol (compound no. 97) Following the indications of step A of example 70, but using l,6-di-O-(2-fluorobenzyl)- 3,4-O-isopropylidene-D-mannitol, the monoalkylation with 4-fluorobenzyl bromide afforded an intermediate that was then alkylated with 2-thienylmethyl chloride. Purification by flash chromatography with 30% EtOAc in hexane afforded the title compound in 75% yield. •H NMR (CDCI 3 ): 2.90 (d, J = 5.5, IH), 2.97 (d, J = 7.5, IH), 3.67 (dd, J = 10.5, 5.0, 2H), 3.78 (m, 4H), 3.88 (t, J = 6.2, IH), 3.92 (t, J = 6.3, IH), 4.54 (d, J = 11.0, IH), 4.61 (s, 4H), 4.69 (d, J = 1 1.8, IH), 4.78 (d, J = 1 1.6, IH), 4.94 (d, J = 12.5, IH), 6.90 - 7.40 (m, 15H). Example 89. Preparation of l,6-di-0-benzyl-2,5-di-O-benzoyI-D-mannitoI (compound no. 109) To a stiπed solution of l,6-di-O-benzyl-3,4-O-isopropylidene-D-mannitol (50 mg, 0.12 mmol), as obtained in example 2, in methylene chloride (2 mL) and pyridine (2 mL) was added dropwise benzoyl chloride (50 mg, 0.36 mmol) at 0°C. The reaction mixture was stiπed for 1 h at 0 °C and 3 h at room temperature. The mixture was poured onto cold 6N HCl (5 mL) and extracted with EtOAc. The organic layer was dried with magnesium sulfate and concentrated in vacuo. The resulting crude material was dissolved in MeOH containing 5% concentrated HCl (3 mL). After stiπing for 5 h, saturated sodium bicarbonate was added and the mixture was extracted with EtOAc. The organic layer was dried over magnesium sulfate, concentrated in vacuo, and the residue was purified by flash chromatography eluting with 50% EtOAc in hexane to yield 85%> of the title compound. Η NMR (CDC1 3 ): 3.28 (d, J = 6.1, IH), 3.90 (m, 2H), 4.02 (t, J = 7.5, IH), 4.51 (d, J = 12.4, IH), 4.57 (d, J = 11.2, IH), 7.03 (s, 5H), 7.43 (t, J = 7.3, 2H), 7.57 (t, J = 7.3, IH), 8.04 (d, J = 7.6, 2H). Example 90. Preparation of l,6-di-O-benzoyl-2,5-di-0-benzyl-D-mannitol (compound no. 110) Following the indications found in example 89, 2,5-di-O-benzyl-3,4-O-isopropylidene-D- mannitol was benzoylated in a 90% yield. Η NMR (CDCI 3 ): 2.83 (d, J = 7.5, IH), 3.89 (m, IH), 4.07 (t, J = 7.5, IH), 4.53 (dd, J = 11.5, 4.5, IH), 4.56 (d, J = 11.5, IH), 4.72 (dd. J = 1 1.5, 7.5, IH), 4.77 (d, J = 1 1.0, IH), 7.25 (m, 5H), 7.40 (t, J = 8.0, 2H), 7.55 (t. J = 7.5, IH), 8.02 (d, J = 8.0, 2H). Example 91. Preparation of l,6-di-0-benzyl-2,5-di-O-(methylthiothioxo)-D-mannitol (compound no. 101) To a solution of l,6-di-O-benzyl-3,4-O-isopropylidene-D-mannitol (40 mg, 0.1 mmol), obtained as in example 2, in DMF (3 mL) was added sodium hydride (7.2 mg, 0.3 mmol). After stiπing for 20 min, carbon disulfide was added and stiπing was continued for 30 min. Methyl iodide (42 mg, 0.3 mmol) was added and the mixture was stiπed for another 15 min. The reaction mixture was quenched with IN HCl and the organic material was extracted with EtOAc. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The residue was dissolved in MeOH containing 3%> HCl (3 mL) and the mixture was stiπed for 3 h. Water was added and the mixture was extracted with EtOAc. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The title compound was obtained in 79%> yield after purification by flash chromatography eluting with 20% EtOAc in hexane. Η NMR (CDC1 3 ): 2.57 (s, 3H), 3.03 (d, J = 6.0, IH), 3.87 (dd, J = 1 1.5, 4.5, IH), 3.94 (dd, J = 1 1.0, 3.5, IH), 4.05 (t, J = 7.5, IH), 4.53 (d, J = 11.0, IH), 4.59 (d, J = 11.0, IH), 5.88 (m, IH), 7.30 (m, 5H). Example 92. Preparation of l,6-di-O-benzyl-2,5-di-0-(benzylthiothioxo)-D-mannitol (compound no. 102) Following the indications of example 91 but substituting methyHodide with berj_ yl bromide, the title compound was obtained in 73% yield. 'H NMR (CDC1 3 ): 3.03 (d, J = 5.5, IH), 3.85 (dd, J = 5.5, 11.0, IH), 3.91 (dd, J = 12.0. 5.5, IH), 4.02 (t, J = 7.5, IH), 4.34 (s, 2H), 4.50 (d, J = 1 1.5, IH), 4.57 (J = 11.5, IH), 5.87 (m, IH), 7.28 (m, 10H) Example 93. Preparation of l,6-di-O-(2-fluorobenzyl)-2-0-(4-fluorobenzyl)-5-O- (methylthiothioxo)-D-mannitol (compound no. 103) Using a procedure similar to the above example 91, substituting l,6-di-O-benzyl-3,4-O- isopropylidene-D-mannitol by 1 ,6-di-O-(2-fluorobenzyl)-2-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol, the title compound was obtained in 79% yield. 'H NMR (CDCI 3 ): 2.55 (s, 3H), 2.88 (d, J = 7.0, IH), 2.99 (d, J = 4.5, IH), 3.70 (m, 2H), 3.79 (d, J = 9.5, IH), 3.95 (m, 2H), 4.23 (t, J = 7.5, IH), 4.63 (m, 6H), 5.87 (m, IH), 6.97 (m, 2H), 7.03 (m, 2H), 7.10 (t, J = 7.0, 2H), 7.28 (m, 4H), 7.38 (m, 2H). Example 94. Preparation of l,2,6-tri-O-benzyI-5-0-(methylthiothioxo)-D-mannitol (compound no. 104) Using a procedure similar to the above example 91, substituting l,6-di-O-benzyl-3,4-O- isopropylidene-D-mannitol by l,2,6-tri-O-benzyl-3,4-O-isopropylidene-D-mannitol, the intermediate of example 71 , the title compound was obtained in 71% yield. Η NMR (CDCI 3 ): 2.53 (s. 3H). 2.90 (d. J = 5.0, 2H), 3.70 (m, 2H), 3.77 (m, IH). 3.91 (m, 2H), 4.00 (t, J = 6.0, IH), 4.53 (m, 3H), 4.56 (d, J = 1 1.5, IH), 4.73 (m, 3H), 5.00 (d, J = 12.5, IH), 7.30 (m, 15H). Example 95. Preparation of l,2,6-tri-0-benzyl-5-O-(allylthiothioxo)-D-mannitol (compound no. 105) Using a procedure similar to the above example 91, substituting l,6-di-O-benzyl-3,4-O- isopropylidene-D-mannitol by 1.2,6-tri-O-benzyl-3,4-O-isopropylidene-D-mannitol, the intermediate of example 71, the title compound was obtained in 81 % yield. 'H NMR (CDCI 3 ): 2.87 (d, J = 7.0, IH), 3.67 (m, 2H), 3.77 (m, 3H), 3.90 (m, 2H), 4.00 (t, J = 6.5, IH), 4.56 (m, 4H), 4.71 (m, 4H), 5.00 (d, J = 11.5, IH), 5.15 (d, J = 10.0, IH), 5.27 (d, J = 15.5, IH), 5.87 (m, IH), 7.30 (m, 15H). Example 96. Preparation of l,6-di-O-benzyl-2-O-(4-fluorobenzyl)-5-O- (methylthiothioxo)-D-mannitol (compound no. 106) Using a procedure similar to the above example 91, substituting l,6-di-O-benzyl-3.4-O- isopropylidene-D-mannitol by 1.6-di-O-benzyl-2-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol. obtained as in example 70 step A, the title compound was obtained in 71% yield. Η NMR (CDCI 3 ): 2.55 (s, 3H), 2.89 (d, J = 7.0, IH), 2.99 (d, J = 4.5. IH), 3.72/(m, 3H), 3.77 (d, J = 9.5, IH), 3.95 (m, 2H), 4.23 (t, J = 7.5. IH), 4.63 (m, 6H), 5.87 (m, IH), 6.98 (m. 2H), 7.03 (m, 2H), 7.11 (t. J = 8.0, 2H), 7.27 (m 4H), 7.38 (m, 2H). Example 97. Preparation of l,2,6-tri-O-benzyl-5-0-(methyloxycarbonyl)-D-mannitol (compound no. 107) Using a procedure similar to the above example 91. l,2,6-tri-O-benzyl-3,4-O- isopropylidene-D-mannitol, the intermediate of example 71, was reacted with methylchloroformate to yield 22% of the title compound. Η NMR (CDCI 3 ): 2.82 (d, J = 6.0, IH), 2.97 (d, J = 6.0, IH), 3.66 (m, 2H), 3.72 (m, IH), 3.77 (s, 3H), 3.79 (m, 2H), 3.86 (t, J = 6.0, IH), 3.99 (t, J = 6.0, IH), 4.30 (dd, J = 12.0, 5.0, IH), 4.54 (s, 2H), 4.51 (d, J = 1 1.5, 2H), 4.72 (d, J = 1 1.0, IH), 4.73 (d, J = 1 1.5, IH), 7.30 (m, 15H). Example 98. Preparation of l,6-di-0-phenyl-2,5-di-0-benzyl-D-mannitol (compound no. 108) Step A. 3,4-O-isopropylidene-D-mannitol-l,2-5,6-diepoxide The title diepoxide was prepared from 3,4-O-isopropylidene-D-mannitol according to the indications found in Heterocycles vol. 25, p. 541 - 548 (1987). Step B. l,6-di-O-phenyl-3,4-O-isopropylidene-D-mannitol To the diepoxide prepared as in step A of this example (500 mg, 2.70 mmol) and phenol (10 g. 1 1.0 mmol) in DMF (10 mL) was added potassium carbonate (180 mg, 1.30 mmol). The reaction mixture was heated at 1 10°C for 7 h and then cooled to room temperature. A saturated solution of sodium bicarbonate (20 mL) was then added. The mixture was extracted with ether, the organic layer was washed with water, dried over magnesium sulfate and concentrated to give an oil that eventually solidified after maintaining it under high vacuum. Purification by flash chromatography using 30%) EtOAc in hexane afforded the title compound in 51 % yield, mp. 1 17°C. Η NMR (CDC1 3 ): 1.38 (s, 3H), 3.81 (s, IH), 4.00 - 4.04 (m, 3H), 4.23 (d, J = 8.3, IH), 6.94 (d, J = 8.2, 2H), 6.96 (t, J = 7.2, 2H), 7.27 (t. J = 8.0, 2H). Step C. l,6-di-O-phenyl-2,5-di-O-benzyl-D-mannitol The product obtained in step A of this example was alkylated with benzyl bromide as indicated in example 3. Purification by flash chromatography eluting with 20% EtOAc provided the title compound (mp. 80 °C) in a 90% yield. 'H NMR (CDC1 3 ): 2.90 (d, J = 5.9, IH), 3.98 (m, IH), 4.08 (t. J = 6.3, IH), 4.13 (dd, J = 7.3, 13.5, IH), 4.27 (dd, J = 1.9, 12.3, IH), 4.63 (d, J = 11.2, IH), 4.81 (d, J = 11.8, IH), 6.95 (m. 4H), 7.30 (m, 10H). Example 99. Preparation of l,6-dideoxy-l,6-dibenzylthio-2,5-O-di-(4-flu jaϊbenzyl)- D-mannitol (compound no. Ill) To a cooled solution (-5°C) of diethylazidocarboxylate (4.5 mg, 0.26 mmol) in THF (1 mL) was added 2.5-di-O-(4-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol (38 mg, 0.086 mmol) in THF (2 mL) and triphenylphosphine (6.8 mg, 0.26 mmol). After 15 min, benzylthiol (32 mg, 3.0 mmol) was added and the reaction mixture was allowed to warm to room temperature. It was stiπed overnight, the solvent was removed in vacuo and the crude material was purified by flash chromatography eluting with 20% EtOAc in hexane to yield the desired l,6-dideoxy-l,6-dibenzylthio-2,5-di-O-(4-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol (32%). The resulting isopropylidene derivative was removed by treatment with methanolic HCl to provide a 91% yield of the title compound. 'H NMR (CDC1 3 ): 2.68 (m, 2H), 2.80 (s, IH), 3.68 (s, 3H), 3.90 (s, IH), 4.45 (d, J = 8.5, IH), 4.60 (d, J = 9.5, IH), 6.90 - 7.30 (m, 9H). Example 100. Preparation of l,6-dideoxy-l,6-di-S-benzoyl-2,5-di-O-(4-fluorobenzyl)- D-mannitol (compound no. 112) Substituting benzylthiol by thiobenzoic acid under the condition described in the previous example, the title compound was obtained in 76% yield. •H NMR (CDCI 3 ): 3.13 (d, J = 5.0, IH), 3.46 (dd, J = 11.0. 5.0, IH), 3.54 (dd, J = 11.0, 5.0, IH), 3.90 (m, 2H), 4.57 (d. J = 11.0, IH), 4.73 (d, J = 1 1.0, IH), 7.20 - 8.00 (m, 9H). Example 101. Preparation of l-O-benzyl-6-O-(2-fluorobenzyl)-2,5-di-0-(4- fluorobenzyl)-D-mannitol (compound no. 63) Step A. l-O-benzyl-6-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol l-O-(2-fluorobenzyl)-3.4-O-isopropylidene-D-mannitol was prepared using the conditions found in example 2. except that 1.5 equivalent of 2-fluorobenzyl bromide was used. Purification by flash chromatography afforded 68% of the monoalkylated product. The resulting product was then alkylated as in example 2 using benzyl bromide. After purification by flash chromatography, eluting with 50%> EtOAc in hexane, 82% of the title compound was obtained. Η NMR (CDC1 3 ): 1.34 (s, 6H), 3.54 - 3.62 (m, 4H), 3.72 - 3.82 (m, 4H), 4.57 (d, J = 3.5, 2H), 4.65 (d, J = 4.5, 2H), 7.00 (t, J = 9.0, IH), 7.1 1 (J = 7.5, IH), 7.22 - 7.30 (m, 2H), 7.32 - 7.35 (m, 4H), 7.42 (t, J = 7.5, IH). Step B. l-O-benzyl-6-O-(2-fluorobenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The alkylation of the product of step A of this example was alkylated with benzyl bromide as in example 4 with a yield of 78%>. Η NMR (CDCI 3 ): 2.48 - 3.02 (m, 2H), 3.65 - 3.89 (m, 6H), 3.90 - 3.95 (m, 2H), 4.53 (s, 4H), 4.56 (d, J = 1 1.5. IH), 4.60 (d, J = 11.5, IH), 4.66 (d, J = 11.0. IH), 4.69 (d, J = 11.0, IH), 6.90 - 7.15 (m. 6H), 7.25 - 7.42 (m, 1 IH). Example 102. Preparation of l,6-di-0-(2-fluorobenzyl)-2-O-benzyl-5-0-(4- fluorobenzyl)-D-mannitoI (compound no. 62) The alkylation of 3,4-O-isopropylidene-D-mannitol was performed according to the indications found in example 2. The l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol was then alkylated with benzyl bromide using the silver oxide conditions as in step A of example 70 . The resulting l,6-di-O-(2-fluorobenzyl)-2-O-benzyl-3,4-O- isopropylidene-D-mannitol was then alkylated with 4-fluorobenzyl bromide as in example 4, leading to 82% of the title product. Η NMR (CDC1 3 ): 2.98 (d, J = 5.5, IH), 3.00 (d, J = 7.5, IH), 3.67 - 3.71 (m, 2H), 3.70 - 3.79 (m, 4H), 3.90 - 3.95 (m, 2H), 4.53 (d, J = 1 1.5, IH), 4.58 (d, J = 11.5, IH), 4.60 (s, 4H), 4.67 (d, J = 1 1.5, IH), 4.73 (d, J = 1 1.5, IH), 6.95 - 7.11 (m, 6H), 7.24 - 7.40 (m, 1 1H). Example 103. Preparation of l,2,6-tri-0-benzyl-5-O-(4-nitrobenzyl)-D-mannitol (compound no. 61) The product of example 71 was further alkylated with 4-nitrobenzyl bromide affording after purification by flash chromatography the title compound. 'H NMR (CDCI 3 ): 2.43 (d, J = 2.5, IH), 2.67 (d, J = 5.5 IH), 3.62 -3.69 (m. 2H) 2.75 (d, J = 12.5, 2H), 3.79 (d, J = 12.5, 2H), 3.78 (dd, J = 9.0, 5.5, IH), 4.07 (d, J = 6.0, IH), 4.52 (s. 2H), 4.56 (s. 2H), 4.68 (s, 2H). 4.68 (d, J = 12.8, IH), 4.90 (d, J = 12.8, 1H),7.25 - 7.35 (m, 15H), 7.44 (d, J = 9.2H), 8.10 (d, J = 7.5, 2H). Example 104. 1,2,5,6-tetra-O-benzyI-D-mannitol - Results on HIV-infected cells The Ki of protease inhibition of 1,2.5,6-tetra-O-benzyl-D-mannitol was found to be 2.0 μM. The assay against HIV infected cells was 4.8 μM. Technical details (antiviral tests): Cells were acutely infected with HIV-1 at a M.O.I, (multiplicity of infection) of 0.01 at 37°C for 2 hours. After adsorption, the cells were washed to remove unabsorbed vims and plated in 96-well or 24-well microplates in culture medium containing the protease inhibitors at various concentrations. The infected cells were grown for 7 or 10 days at 37°C with the culture medium replaced every 3 to 4 days with fresh medium containing inhibitors. Aliquots from the cell culture supernatants were collected and frozen at -70°C for subsequent viral titer determination. Reverse transcriptase activity was measured by standard procedures. The samples were centrifuged at 4°C for 45 min at 45000 RPM and the virus pellets resuspended in 500 μL of buffer (Tris-HCl 10 mM, pH 7. 8, NaCl 100 mM, EDTA 1 mM) containing 0.1 % Triton X-100. For the assay, 20 μL of suspension was added to 40 μL of reaction buffer (Tris-HCl 60 mM, pH 8.0, MgCl, 6 mM, KC1 25 mM, DTT 1 mM, 125 ng poly(rA) and oligo(dT)12-18, and 5 μCi of 3 H-TTP). The reaction was done at 37°C for 1 h after which the incorporated radioactivity was precipitated with TCA. After filtfation, the radioactivity incorporated by the viral reverse transcriptase in the template was measured with a scintillation counter. P24 determination was done in cell-free supematants using the p24 antigen-capture assay of Coulter Immunology or S AIC Frederick, according to the manufacturer's recommendations . Inhibition of syncytia formation was assessed by periodic microscope examination under low magnification of infected cells incubated with the protease inhibitors at different concentrations. Example 105. 1,2,5,6-tetra-O-benzyI-D-mannitol - toxicity on cells The Ki of protease inhibition of 1,2,5,6-tetra-O-benzyl-D-mannitol was found to be 2.0 μM and the cytotoxicity was found to be 15 μM. Technical details: Two assays were performed to evaluate the potentiel toxicity of the compounds in infected cells: 1) Briefly, cells were grown in 96-well microtiter plates at 37°C in complete culture medium in the presence of the compound to test. Control cells grown in the absence of the compound received the same amount of solvent used to dissolve th inhibitor (in thjfe case, dimethylsulfoxide at a final concentration of 0.1 to 0.3%>). After 7 or 10 days, MTT was added to the cultures for 4 hours at 37°C as described in the literature (Schwartz et al., AIDS Res. Hum. Retrov. 4: 441-448, 1988; Mosmann, J. Immunol. Meth., 65: 55-63, 1983) and the changes in absorbance associated with metabolism of MTT by viable cells was monitored with an ELISA microplate reader at a test wavelength of 540 nm. 2) The cells were grown as described above in 24- well microplates or 25 -cm tissue culture flasks in the presence or absence of the tested compounds, and the cell viability after 7 or 10 days was determined by the trypan blue exclusion test, using a hemacytometer and a microscope at 100X magnification. The compounds listed in Table 4 were prepared by following Schemes 1, 2, 3 or 4 above. The activities of the compounds are also listed in the same table demonstrating their potential usefulness. In Table 4 are shown compounds of formula 1 (formulala), as defined above, for the description of the mannitol derivatives found in Table 1. For the synthesis of the following D-mannitol derivatives several benzyl halides were made from commercially available benzyl alcohols using standard reaction conditions. Table 4. Di- tri- and tetra-substituted D-mannitol derivatives. Example 106. Preparation of l,6-di-0-(3,4-dihydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D- mannitol (compound no. 113) Step A. l,6-di-O-(3,4-dibenzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The alkylation of 3,4-O-isopropylidene-D-mannitol with 3,4-dibenzyloxybenzyl chloride was caπied out as described in example 2. The resulting l,6-di-O-(3,4-dibenzyloxybenzyl)-3,4-O- isopropylidene-D-mannitol (45%) was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane:EtΟAc, 1 : 1) provided 30%) of the desired product. Η NMR (CDC1 3 ): 3.02 (s, 2H), 3.59 - 3.62 (m, 2H), 3.67 - 3.74 (m, 4H), 3.92 (d, J = 6.5, 2H), 4.44 (s, 2H), 4.53 (d, J = 1 1.0, 2H), 4.65 (d, J = 11.5, 2H), 5.11 (s, 4H), 5.15 (s, 4H), 6.82 (d, J = 8.0, 2H), 6.89 (d, J = 9.0, 2H), 6.95 - 6.99 (m, 6H), 7.24 - 7.38 (m, 17H), 7.44 (t, J = 8.0, 7H). Step B. l,6-di-O-(3,4-dihydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH,C1,. The title' compound (47%) was thus obtained. Η NMR (CDC1 3 ): 3.66 - 3.77 (m. 6H), 3.85 - 3.87 (m, 4H), 3.95 (t, J = 7.0, 2H), 4.42 (s, 4H), 4.58 (d. J = 1 1.0, 2H), 4.75 (d, J = 1 1.5, 2H), 6.71 (d. J = 8.0, 2H), 6.79 (d, J = 7.5, 2H). 6.89 (s, 2H), 7.06 (t, J = 8.0, 4H), 7.36 - 7.41 (m, 4H), 7.81 (s, 4H). Example 107. Preparation of l,6-di-O-(2-fluoro-6-hydroxybenzyl)-2,5-di-O-(4- fluorobenzyI)-D-mannitol (compound no. 114) Step A. 1 ,6-di-O-(2-fluoro-6-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 130) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluoro-6-benzyloxybenzyl chloride was caπied out as described in example 2. The resulting 1 ,6-di-O-(2-fluoro-6- benzyloxybenzyl)-3,4-O-isopropylidene-D-mannitol (54%) was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane: EtOAc, 7:3) provided 34%) of the desired product. Η NMR (CDCI 3 ): 3.05 (d, J = 6.5, 2H), 3.63 - 3.66 (m, 4H), 3.74 - 3.77 (m, 2H), 3.81 (t, J = 5.5, 2H), 4.45 (d, J = 1 1.5, 2H), 4.60 (d, J = 7.5, 2H), 4.63 - 4.71 (m, 4H), 5.05 (s, 4H), 6.67 - 6.71 (m, 4H), 6.89 - 6.97 (m, 4H), 7.16 - 7.33 (m, 12H), 7.37 (d, J = 7.5, 4H). Step B. 1 ,6-di-O-(2-fluoro-6-hydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography to yield 71%) of the title product. 'H NMR (CDClj): 2.95 (s, 2H). 3.69 (t, J = 3.0. 2H), 3.76 - 3.77 (m, 4H), 3.92 (d, J = 7.0, 2H), 4.49 (d, J = 1 1.0, 2H), 4.62 (d, J = 1 1.0, 2H), 4.74 (d, J = 12.5, 2H), 4.80 (d, J = 1 1.5, 2H), 6.59 (t, J = 9.0, 2H), 6.65 (d, J = 8.5, 2H), 6.98 (t, J = 7.5, 4H), 7.13 (q, J = 7.5, 2H), 7.26 (t, J = 6.0, 4H), 7.82 (s, 2H). Example 108. Preparation of l,6-di-0-(5-fluoro-2-hydroxybenzyl)-2,5-di-0-(4- fluorobenzyl)-D-mannitol (compound no. 115) Step A. 1 ,6-di-O-(5-fluoro-2-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 131) The alkylation of 3,4-O-isopropylidene-D-mannitol with 5 -fluoro-2-benzyloxy benzyl chloride was caπied out as described in example 2. The resulting l,6-di-O-(5-fluoro-2-hydroxybenzyl)- 3,4-O-isopropylidene-D-mannitol (25%) was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane:EtOAc, 7:3) provided 29% of the desired product. Η NMR (CDCI 3 ): 3.07 (d, J = 6.0, 2H), 3.73 - 3.81 (m, 6H), 3.96 (t, J = 5.0, 2H), 4.62 - 4.63 (m, 4H), 4.71 (d, J = 11.5. 2H), 4.80 (d, J = 11.5, 2H), 5.05 (s, 4H), 6.84 - 6.86 (m, 2H), 6.98 (t, J = 8.5, 6H), 7.16 (d, J = 8.0, 2H), 7.28 (t, J = 6.5, 4H), 7.32 - 7.40 (m, 10H). Step B. 1 ,6-di-O-(5-fluoro-2-hydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH,C1, yielded 60% of the title product. LC-MS: 646 (M + ). Example 109. Preparation of l,6-di-O-(2-methoxybenzyl)-2,5-di-0-(4-fluorobenzyl)-D- mannitol (compound no. 116) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2 -methoxy benzyl chloride was carried out as described in example 2. The resulting l,6-di-O-(2-methoxybenzyl)-3,4-O-isopropylidene- D-mannitol was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane:EtOAc, 7:3) provided 36%> of the desired product. Η NMR (CDC1 3 ): 3.25 (d, J = 5.5, 2H), 3.74 - 3.85 (m, 12H), 3.98 (t, J = 5.5, 2H), 4.59 - 4.66 (m, 6H), 4.73 (d, J = 11.5, 2H), 6.89 (d, J = 8.0, 2H), 6.95 - 7.02 (m, 6H), 7.31 (t, J = 6.5, 6H), 7.38 (d, J = 7.0, 2H). Example 110. Preparation of l,6-di-0-(2-fluoro-4-hydroxybenzyl)-2,5-di-O-(4- fluorobenzyι)-D-mannitol (compound no. 117) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluoro-4-benzyloxybenzyl chforide was carried out as described in example 2. The resulting 1.6-di-O-(2-fluoro-4- benzyloxybenzyl)-3,4-O-isopropylidene-D-mannitol (65%) was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. The resulting compound. l,6-di-O-(2-fluoro-4-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol, was isolated (30%) and immediately hydrogenolyzed according to the conditions of example 113 step B. Flash chromatography eluting with hexane:EtOAc, 7:3 yielded 24% of the title compound. Η NMR (acetone-d 6 ): 3.70 - 3.77 (m, 6H), 3.91 - 3.96 (m, 4H), 4.52 (q, J = 7.0, 4H), 4.58 (d, J = 12.0, 2H), 4.74 (d, J = 1 1.0, 2H), 6.59 (d, J = 13.5, 2H), 6.60 (d, J = 9.5, 2H), 7.04 (t, J = 8,0, 4H), 7.28 (t, J = 8.5, 2H), 7.37 (t, J = 6.0, 4H), 8.76 (s, 2H). Example 111. Preparation of l,6-di-0-(3-hydroxy-2-methylbenzyl)-2,5-di-O-(4- fluorobenzyl)-D-mannitol (compound no. 118) and l-0-benzyl-2,5-di-0-(4-fluorobenzyl)-6- O-(3-hydroxy-2-methylbenzyι)-D-mannitol (compound no. 122) The alkylation of 3,4-O-isopropylidene-D-mannitol with a mixture of 3-benzyloxy-2- methylbenzyl chloride and benzyl bromide (2:1) was caπied out as described in example 2. The resulting 1.6-di-O-(3-benzyloxy-2-methylbenzyl)-3,4-O-isopropylidene-D-mannitol and 1-O- benzyl-3,4-O-isopropylidene-6-O-(3-benzyloxy-2-methylbenzyl)-D-mannitol were not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. The intermediates, l,6-di-O-(3-benzyloxy-2-methylbenzyl)-2,5-di-O-(4- fluorobenzyl)-D-mannitol and 1 -O-benzyl-2,5-di-O-(4-fluorobenzyl)-6-O-(3-hydroxy-2- methylbenzyl)-D-mannitol, were isolated and immediately hydrogenolyzed according to/the conditions of example 113 step B. Flash chromatography eluting with hexane:EtOAc, 7:3 yielded 17% of compound no. 118 and 7% of compound no. 122. l,6-di-O-(3-hydroxy-2-methylbenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 118) •H NMR (CDC1 3 ): 2.19 (s, 6H), 3.09 (d, J = 5.5, 2H), 3.65 - 3.68 (m, 2H), 3.72 - 3.76 (m, 4H), 3.94 (t, J = 5.0, 2H), 4.50 - 4.57 (m, 6H), 4.69 (d, J = 6.5, 2H), 5.28 (s, 2H), 6.75 (d, J = 8.5. 2H), 6.89 ( d, J = 7.5, 2H), 6.97 - 7.04 (m, 5H), 7.25 - 7.27 (m, 4H), 7.31 - 7.36 (m, IH). l-O-benzyl-2,5-di-O-(4-fluorobenzyl)-6-O-(3-hydroxy-2-methylbenzyl)-D-mannitol (compound no. 122) Η NMR (CDC1 3 ): 2.20 (s, 3H), 3.03 (d, J = 5.5, 2H), 3.66 - 3.68 (m, 2H), 3.73 - 3.77 (m. 4H), 3.94 (s, 2H), 4.51 - 4.57 (m, 6H), 4.67 (d, J = 3.0, IH), 4.70 (d, J = 3.0, IH), 4.77 (s, IH), 6.76 (d, J = 8.0, IH), 6.91 (d, J = 7.0, IH), 6.99 (t, J = 8.5, 4H), 7.04 (t, J = 8.0, IH), 7.26 - 7.35 (m, 9H). Example 112. Preparation of l,6-di-0-(2-fluoro-6-methoxybenzyl)-2,5-di-O-(4- fluorobenzyl)-D-mannitol (compound no. 119) The product of example 107 (24 mg, 0.037 mmol) dissolved in acetone (3 mL) was treated with methyl iodide (42 mg, 18.5 μL, 0.29 mmol) and K,CO 3 (30 mg, 0.22 mmol). The reaction mixture was heated at reflux for 3 h. Then a solution of saturated NH 4 C1 was added and two extractions with ethyl acetate were performed. The combined organic phases were washed with brine and dried over MgSO 4 . The crude was purified on silica gel using hexane:EtOAc, 1 : 1 to yield 28%> of the title compound. Η NMR (CDC1 3 ): 3.15 (d, J = 5.5. 2H), 3.67 - 3.72 (m, 4H), 3.80 - 3.87 (m, 10H), 4.53 (d, J = 11.5, 2H), 4.60 - 4.68 (m, 6H), 6.67 - 6.73 (m, 4H), 6.97 (t, J = 7.5, 4H), 7.24 - 7.27 (m, 6H). Example 113. Preparation of l,6-di-0-(2-fluorobenzyI)-2,5-di-O-(3-hydroxy-2- methylbenzyl)-D-mannitol (compound no. 120) Step A. 1 ,6-di-O-(2-fluorobenzyl)-2,5-di-O-(3-benzyloxy-2-methylbenzyl)-D-mannitol The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol was not characterized but reacted with 3-benzyloxy-2-methylbenzyl chloride according to the conditions described in example 4. Purification by flash chromatography eluting with hexane:EtOAc, 7:3 gave 26%> of the title compound. 'H NMR (CDCI 3 ): 2.33 (s, 6H), 3.09 (d, J = 5.5, 2H), 3.78 - 3.80 (m, 2H), 3.86 - 3.89 (m, 4H), 4.02 (t, J = 5.0, 2H), 4.65 - 4.70 (m, 6H), 4.84 (d, J = 11.5, 2H), 5.1 1 (s, 4H), 6.92 (d, J = 8.5, 2H), 7.02 (d, J = 7.5, 2H), 7.08 (t, J = 9.5, 2H), 7.15 (q, J = 7.0, 4H), 7.30 (q, J = 7.0, 2H), 7.38 (t, J = 7.0, 2H), 7.43 - 7.51 (m, 10H). Step B. l,6-di-O-(2-fluorobenzyl)-2,5-di-O-(3-hydroxy-2-methylbenzyr).-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH,C1 2 . The title compound (80%) was thus obtained. LC-MS: 639 (M + ). Example 114. Preparation of l,6-di-O-(2-fluorobenzyl)-2-O-benzyl-5-O-(3-hydroxy-2- methylbenzyl)-D-mannitol (compound no. 121) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was carried out as described in example 2. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol was not characterized but reacted with a mixture of 3-benzyloxy-2-methylbenzyl chloride and benzyl bromide (1 :2) according to the conditions described in example 4. The resulting l ,6-di-O-(2-fluorobenzyl)-2-O-benzyl-5-O-(3-benzyloxy-2-methylbenzyl)-D-mannitol (52%>) was hydrogenolyzed according to the conditions of example 113 step B. Flash chromatography eluting with 5% methanol in CH,C1, yielded 14% of the desired product 'H NMR (CDC1 3 ): 2.18 (s, 3H), 3.67 (d, J = 7.0, IH), 3.71 (d, J = 7.5, IH), 3.77 - 3.82 (m, 4H), 3.96 - 4.03 (m, 4H), 4.57 (d, J = 11.0, IH), 4.61 - 4.68 (m, 5H), 4.79 (d, J = 11.5, 2H), 6.77 (d, J = 8.0, IH), 6.87 (d, J = 7.0, IH), 6.93 (t, J = 7.5, IH), 7.11 (t, J = 9.5, 2H), 7.16 (t, J = 7.5, 2H), 7.24 - 7.36 (m, 7H), 7.52 (s, 2H), 8.07 (s, IH). Example 115. Preparation of l,6-di-0-(2-fluorobenzyl)-2,5-di-O-(2-hych oxybenzyl)-ϊ>- mannitol (compound no. 123) Step A. l,6-di-O-(2-fluorobenzyl)-2,5-di-O-(2-benzyloxybenzyl)-D-mannitol (compound no. 132) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2. The resulting l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D- mannitol was not characterized but reacted with 2-benzyloxy-2-benzyl chloride according to the conditions described in example 4. Purification by flash chromatography eluting with hexane:EtOAc, 7:3 gave 32%) of the title compound. Η NMR (CDC1 3 ): 3.10 (d, J = 5.5, 2H), 3.66 - 3.68 (m, 2H), 3.75 - 3.77 (m, 4H), 3.92 (t, J = 6.5, 2H), 4.55 (d, J = 12.0, 2H), 4.59 (d, J = 13.0, 2H), 4.67 (d, J = 11.5, 2H), 4.82 (d, J = 11.5, 2H), 5.08 (s, 4H), 6.90 - 6.94 (m, 4H), 6.97 - 7.08 (m, 4H), 7.22 - 7.46 (m, 18H). Step B. 1.6-di-O-(2-fluorobenzyl)-2,5-di-O-(2-hydroxybenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5%> palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH,C1,. The title compound (49%) was thus obtained. Η NMR (CDC1 3 ): 3.25 (d, J = 5.5, 2H), 3.65 - 3.68 (m, 2H), 3.76 - 3.82 (m, 4H), 3.88 (t, J = 4.0, 2H), 4.61 - 4.66 (m. 6H), 4.76 (d, J = 10.5, 2H), 6.81 (t, J = 7.0, 2H), 6.86 (d>J = 8.5, 2U)J.0l - 7.05 (m, 4H), 7.10 (t, J = 7.5, 2H), 7.19 (t, J = 8.0, 2H), 7.25 - 7.29 (m, 2H), 7.39 (t, J = 8.0, 2H), 7.42 (s, 2H). Example 116. Preparation of l,6-di-0-(2-fluorobenzyl)-2-O-(2-hydroxybenzyl)-5-O-(4- fluorobenzyl)-D-mannitol (compound no. 124) Step A. 1 ,6-di-O-(2-fluorobenzyl)-2-O-(2-benzyloxybenzyl)-5-O-(4-fluorobenzyl)-D-mannitol (compound no. 133) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-fluorobenzyl bromide was caπied out as described in example 2. The l,6-di-O-(2-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol was then alkylated with 4-fluorobenzyl bromide using the silver oxide conditions as described in step A of example 70 . The resulting l,6-di-O-(2-fluorobenzyl)-2-O-(4-fluorobenzyl-3,4-O- isopropylidene-D-mannitol (80%>) was then further alkylated with 2-benzyloxybenzyl chloride as in example 4. leading to 48% of the title product. Η NMR (CDCl j ): 2.99 (d, J = 7.0, 2H), 3.07 (d, J = 5.5, IH), 3.62 - 3.76 (m, 5H), 3.81 (q, J = 5.0, IH), 3.87 (t, J = 5.5, IH), 3.92 (t, J = 6.0, IH), 4.49 (d, J = 12.0, IH), 4.53 - 4.61 (m, 4H), 4.65 (d, J = 1 1.5, IH), 4.70 (d, J = 1 1.0, IH), 4.81 (d, J = 11.5, IH), 5.06 (s, 2H), 6.90 - 6.95 (m, 4H), 6.99 - 7.10 (m, 4H), 7.04 - 7.22 (m, 13H). Step B. 1 ,6-di-O-(2-fluorobenzyl)-2-O-(2-hydroxybenzyl)-5-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcøal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH,C1, to give 84% of the title compound. Η NMR (CDC1 3 ): 3.68 - 3.76 (m, 3H), 3.78 - 3.86 (m, 3H), 3.90 (d, J = 6.5, IH), 3.94 (d, J = 5.5, IH), 4.56 (d, J = 12.0, IH), 4.61 (s, 2H), 4.66 - 4.72 (m, 4H), 4.82 (d, J = 10.5, IH), 6.84 (t, J = 7.5, IH), 6.91 (d. J = 7.5. IH), 6.99 - 7.07 (m, 5H), 7.10 - 7.16 (m, 2H), 7.21 - 7.32 (m, 5H), 7.36 (t, J = 7.5, IH), 7.45 (t, J = 7.5, IH). Example 117. Preparation of l,6-di-O-(2-fluorobenzyl)-2-O-(3,5-dihydroxybenzyl)-5-0-(4- fluorobenzyl)-D-mannitoI (compound no. 125) By following the conditions described in the example 116 and substituting 2-benzyloxybenzyl chloride by 3,5-dibenzyloxybenzyl chloride, the title compound was obtained in 22% overall yield. Η NMR (CDClj): 3.26 (s, IH), 3.33 (s, IH), 3.65 - 3.75 (m, 6H), 3.96 (s, IH), 4.00 (d, J = 5.0, IH), 4.35 (d, J = 11.5, IH), 4.49 - 4.62 (m, 7H), 6.19 (s, IH), 6.29 (s, 2H). 6.43 (s. 2H), 6.92 (t, J = 9.0, 2H), 7.00 (t, J = 9.5, 2H), 7.06 (t, J = 7.5, 2H), 7.20 - 7.25 (m, 4H), 7.34 (s, 2H). Example 118. Preparation of l,6-di-O-(2-fluorobenzyl)-2-O-(4-hydroxybenzyl)-5-0-(4- fluorobenzyl)-D-mannitol (compound no. 126) By following the conditions described in the example 116 and substituting'-i-benzyloxybejlzyl chloride by 4-benzyloxybenzyl chloride, the intermediate, 1 ,6-di-O-(2-fluorobenzyl)-2-O-(4- benzyloxybenzyl)-5-O-(4-fluorobenzyl)-D-mannitol, was obtained in 28 % yield (step A) and the title compound was obtained in 73%> yield (step B). Step A. 1 ,6-di-O-(2-fluorobenzyl)-2-O-(4-benzyloxybenzyl)-5-O-(4-fluorobenzyl)-D-mannitol (compound no. 134) Η NMR (CDC1 3 ): 3.00 (d, J = 4.5, 2H), 3.67 - 3.78 (m, 6H), 3.92 (t, J = 6.0, 2H), 4.51 - 4.68 (m, 8H), 5.03 (s, 2H), 6.91 (d, J = 8.5, 2H), 6.96 (t, J = 9.0, 2H), 7.02 (t, J = 9.0, 2H), 7.09 (t, J = 7.5, 2H), 7.22 - 7.27 (m, 6H), 7.31 (t, J = 7.0, IH), 7.35 - 7.42 (m, 6H). Step B. 1 ,6-di-O-(2-fluorobenzyl)-2-O-(4-hydroxybenzyl)-5-O-(4-fluorobenzyl)-D-mannitol Η NMR (CDC1 3 ): 3.10 (s, IH), 3.20 (s, IH), 3.67 - 3.71 (m, 2H), 3.74 - 3.77 (m, 4H), 3.95 (s, 2H), 4.47 (d, J = 1 1.0, IH), 4.53 - 4.67 (m, 7H), 5.99 (s, IH), 6.68 (d, J = 8.5, 2H). 6.95 (t, J = 9.0. 2H), 7.02 (t, J = 9.0, 2H), 7.07 - 7.12 (m, 4H), 7.24 - 7.28 (m, 4H), 7.37 (s, 2H). Example 119. Preparation of l-0-(3,5-dihydroxybenzyl)-2-O-benzyl-5-O-(4-fluorobenzyl)- 6-O-(2-fluorobenzyl)-D-mannitol (compound no. 127) Step A. l,2;3,4-di-O-isopropylidene-6-O-(2-fluorobenzyl)-D-mannitol A solution of l,2;3,4-di-O-isopropylidene (10 g, 38.1 mmol) prepared according to a procedure adapted from Morpain C. et al.. J. Chem. Soc. Perkin Trans., 1379-138^ (1979) and dib"utyltin oxide (12.3 g, 49.4 mmol), in toluene (250 mL) was refluxed for a period of 4.5 h eliminating the water using a Dean-Stark apparatus. The reaction mixture was concentrated to dryness in vacuo. To the residue was added DMF (225 mL) and cesium fluoride (9.3 g, 1.6 eq.). The resulting solution was stiπed at 60 °C for 5 h. At that point, 2-fluorobenzyl bromide (9.1 mL, 76.8 mmol) was added and the reaction mixture was heated at 60 °C for an additional period of 16 h. The reaction mixture was quenched by the addition of EtOAc and saturated NH 4 C1. The aqueous phase was extracted twice with EtOAc. The combined organic layers were washed with brine, dried over MgSO 4 and concentrated in vacuo. The cmde was then purified by flash chromatography eluting with a mixture of EtOAc/hexane (1/4), affording 5.54 g (39%) of the title compound. Η NMR (CDC1 3 ): 1.36 (s, 6H), 1.37 (s, 6H), 1.44 (s, 3H), 3.45 (s, IH), 3.63 (dd, J = 9.0, 5.5, IH), 3.77 (d, J = 11.5, IH), 3.84 - 3.87 (m, 2H), 3.92 (t, J = 7.0, IH), 4.00 (t, J = 6.5, IH), 4.10 (q, J = 6.5, IH), 4.15 - 4.18 (m, IH), 4.60 (d, J = 12.5, IH), 4.70 (d, J = 12.5, IH), 7.01 - 7.06 (m, IH), 7.14 (q, J = 7.5, IH), 7.24 - 7.27 (m, IH), 7.42 - 7.48 (m, IH). Step B. l-O-(2-fluorobenzyl)-2-O-(4-fluorobenzyl)-3,4-O-isopropylidene-D-mannitol To a solution of the product prepared in step A of this example (5.51 g, 15 mmol) in DMF (150 mL) was added sodium hydride (2.87 g; 1 19.6 mmol). The mixture was stiπed for 24 h at room temperature. 4-Fluorobenzyl bromide (5.5 mL, 45.9 mmol) was added and the mixture was stiπed overnight at room temperature. The reaction mixture was quenched with IN HCl and extracted twice with EtOAc. The combined organic layers were washed with brine, dried over MgSO 4 and concentrated in vacuo. The residue was then dissolved in acetic acid (30 nL) and water was added (30 mL). The solution was heated at 40 °C for 3h. The mixture was then neutralized with potassium bicarbonate and extracted with EtOAc. The organic layers were washed with brine, dried over MgSO 4 and concentrated in vacuo. The cmde product was purified by flash chromatography eluting with 50% EtOAc in hexane to afford 1.58 g (24%) of the title compound as an oil. Η NMR (CDC1 3 ): 1.36 (s, 6H), 1.38 (s, 6H), 2.30 (s, IH), 3.62 - 3.76 (m, 6H), 3.88 (t, J = 7.5, IH), 3.94 (d, J = 11.0. IH), 3.99 (t, J = 7.5, IH), 4.59 (d, J = 1 1.5, IH), 4.64 (d, J = 11.5, IH), 4.67 (d, J = 12.0, IH), 4.87 (d, J = 1 1.5, IH), 7.02 - 7.09 (m, 2H), 7.16 (t, J = 7.5, IH), 7.27 - 7.32 (m, 3H), 7.43 (t, J = 7.5, IH). Step C. l-O-(3,5-dibenzyloxybenzyl)-5-O-(4-fluorobenzyl)-6-O-(2-fluorobenzyl)-3,4-O- isopropylidene-D-mannitol A solution of the product prepared in step B of this example (294 mg, 0.67 mmol) dibutyltin oxide (184 mg, 0.74 mmol). in toluene (25 mL) was refluxed for a period of 4.5 h eliminating the water using a Dean-Stark apparatus. The reaction mixture was concentrated to dryness in vacuo. To the residue was added DMF (9 mL) and cesium fluoride (207 mg, 1.36 mmol) in DMF (9 mL) was stiπed at 80 °C for 2.5 h. 3,5-Dibenzyloxybenzyl chloride (342 mg, 1.0 mmol) was added and the reaction mixture was stiπed at 60 °C overnight. The reaction mixture was quenched with saturated NH 4 C1 and extracted with EtOAc. The organic phase was washed with brine, dried over MgSO 4 and concentrated in vacuo. The residue was purified by flash chromatography eluting with 30%) EtOAc in hexane to afford 352 mg (71 >) of the title compound as an oil. Η NMR (CDCI 3 ): 1.37 (s, 3H), 1.38 (s, 3H), 3.12 (d, J = 3.5, IH), 3.58 (dd, J = 10.5, 6.0, IH), 3.69 - 3.81 (m, 4H), 3.90 (d, J = 8.0. IH), 3.99 (t, J = 7.0, IH), 4.11 (t, J = 6.5, IH), 4.53 (s, 2H), 4.62 - 4.67 (m, 3H), 4.78 (d. J = 11.5, IH), 5.04 (s, 4H), 6.57 (s, IH), 6.64 (s, 2H), 6.98 (t, J = 8.0, 2H), 7.06 (t, J = 9.5, IH), 7.14 (t. J = 7.5, IH), 7.23 - 7.44 (m, 4H). Step D. Preparation of l-O-3,5-(dibenzyloxybenzyl)-2-O-benzyl-5-O-(4-fluorobenzyl)-6-O-(2- fluorobenzyl)-D-mannitol The product obtained in step C of this example (300 mg, 0.41 mmol) was alkylated under the conditions described in step B of this example by substituting 4-fluorobenzyl bromide with benzyl bromide and afforded 272 mg (40%) of the desired product as an oil after purification by flash chromatography eluting with 30%) EtOAc in hexane. Η NMR (CDCI 3 ): 3.02 (t, J = 6.0, 2H), 3.67 - 3.80 (m, 6H), 3.96 (d, J = 3.0, 2H), 4.51 (s, 2H), 4.56 - 4.64 (m, 4H), 4.69 (d, J = 11.5, IH), 4.75 (d, J = 12.0, IH), 5.01 (s, 2H), 6.57 (s. IH), 6.61 (s, 2H), 6.98 (t, J = 7.5, 2H), 7.04 (t. J = 9.5, IH), 7.11 (t, J = 7.5, IH), 7.26 - 7.42 (m, 19H). Step E. l-O-(3,5-dihydroxybenzyl)-2-O-benzyl-5-O-(4-fluorobenzyl)-6-O-(2-fluorobenzyl)-D- mannitol To a solution of the product obtained in step D of this example (105 mg, 0.13 mmol) in EtAOc (7.5 mL) was added succescively 2 drops of pyridine and 5% Pd/C (105 mg). The mixture was stiπed for 45 min under an atmosphere of hydrogen. The solution wa hen filtered, evaporated in vacuo and the residue was purified by flash chromatography eluting with 5% MeOH in CH,C1,, affording 40 mg (49%>) of the title compound as a clear oil. Η NMR (CDC1 3 ): 3.23 - 3.27 (m, 2H), 3.60 - 3.70 (m, 3H), 3.73 - 3.78 (m, 2H), 3.83 (q, J = 5.0, IH). 4.04 (t, J = 3.5, IH), 4.09 (t, J = 6.0, IH), 4.32 (d, J = 12.5, IH), 4.42 (d, J = 13.0, IH), 4.55 (d. J = 11.5, 2H), 4.61 (s, 2H), 4.66 (t, J = 11.5, 2H), 6.21 (s, IH), 6.31 (s, 2H), 6.41 (s, 2H), 6.95 (t, J = 9.0, 2H), 7.02 (t, J = 9.0, IH), 7.09 (t, J = 7.0, IH), 7.24 - 7.30 (m, 8H), 7.37 (t, J = 7.5, IH). Example 120. Preparation of l-O-(2-fluoro-4-hydroxybenzyI)-2-0-(benzyl)-5-0-(4- fluorobenzyl)-6-O-(2-fluorobenzyl)-D-mannitol (compound no. 128) By following the conditions described in the example 1 19 (steps C, D and E) and substituting 3,5-dibenzyloxybenzyl chloride by 4-benzyloxy-2-fluorobenzyl chloride, the intermediates, 1-O- (4-benzyloxy-2-fluorobenzyl)-5-O-(4-fluorobenzyl)-6-O-(2-fluorobenzyl)-3,4-O-isopropylidene- D-mannitol (80%>) and l-O-(2-fluoro-4-benzyloxybenzyl)-2-O-(benzyl)-5-O-(4-fluorobenzyl)-6- O-(2-fluorobenzyl)-D-mannitol (28%) were obtained as well as the title compound in 46% yield. l-O-(2-fluoro-4-benzyloxybenzyl)-2-O-(benzyl)-5-O-(4-fluorobenzyl)-6-O-(2-fluorobenzyl)-D- mannitol (compound no. 135) Η NMR (CDCI 3 ): 2.98 (t, J = 7.0, 2H), 3.66 - 3.79 (m, 6H), 3.92 (q, J = 6.0, 2H), 4.49 - 4.64 (m, 6H), 4.67 - 4.72 (m, 2H), 5.03 (s, 2H), 6.66 - 6.72 (m, 2H), 6.97 (t, J = 9.0, IH), 7.03 (t, J = 9.0, IH), 7.10 (t, J = 7.5, IH), 7.23 - 7.34 (m, 10H), 7.37 - 7.42 (m, 5H). l-O-(2-fluoro-4-hydroxybenzyl)-2-O-(benzyl)-5-O-(4-fluorobenzyl)-6-O-(2-fluorobenzyl)-D- mannitol Η NMR (CDC1 3 ): 3.13 (s, IH), 3.20 (s, IH), 3.68 - 3.69 (m, 2H), 3.74 - 3.75 (m, 4H), 3.94 (s, IH), 3.98 (s, IH), 4.46 - 4.71 (m, 8H), 6.33 (s, IH), 6.45 (d, J = 9.5, 2H), 6.95 (d, J = 8.5, 2H), 7.02 (t, J = 9.0, IH), 7.08 (s, 2H), 7.25 - 7.29 (m, 8H), 7.36 (t, J = 6.5, IH). Example 121. Preparation of l-O-(3,5-dimethoxybenzyl)-2-O-(benzyl)-5-0-(4- fluorobenzyl)-6-0-(2-fluorobenzyl)-D-mannitol (compound no. 129) By following the conditions described in the example 112 the title compound was obtained in 65% yield. Η NMR (CDCI 3 ): 3.02 (t, J = 4.0, 2H), 3.67 - 3.79 (m, 12H), 3.91 - 3.98 (m, 2H), 4.51 (s, 2H), 4.56 - 4.77 (m, 6H), 6.40 (s, IH), 6.51 (s, 2H), 6.99 (t, J = 8.0, 2H), 7.05 (t, J = 9.5, IH), 7.12 (t, J = 7.5, IH), 7.28 - 7.33 (m, 8H), 7.40 (t, J = 7.5, IH). Example 122. Preparation of l,6-di-0-(2-hy droxybenzyl)-2,5-di-0-(4-fluorobenzyl)-D- mannitol (compound no. 136) Step A. 1 ,6-di-O-(2-benzyloxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 64) The alkylation of 3,4-O-isopropylidene-D-mannitol with 2-benzyloxybenzyl chloride was-caπied out as described in example 2. The resulting l,6-di-O-(2-benzyloxybenzyl)-3,4-O- isopropylidene-D-mannitol (55%) was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane: EtOAc, 1 :1) provided 40% of the desired product. Η NMR (CDC1 3 ): 3.30 (d, J = 5.5, 2H), 3.82 - 3.93 (m, 6H), 4.08 (t, J = 5.5, 2H), 4.65 (d, J = 11.5, 2H), 4.78 (q, J = 7.0, 6H), 5.15 (s, 4H), 7.01 - 7.08 (m, 8H), 7.35 (t, J = 7.0, 4H), 7.40 (t, J 7.5, 2H), 7.46 (t, J = 7.5, 4H), 7.52 (d, J = 7.0, 6H). Step B. l,6-di-O-(2-hydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5%> palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH 2 C1,. The title compound (78%) was thus obtained. Η NMR (CDCI 3 ): 2.97 (d, J = 6.5, 2H), 3.71 - 3.76 (m, 6H), 3.96 (t, J = 6.0, 2H), 4.51 (d, J = 1 1.0, 2H), 4.63 - 4.72 (m, 6H), 6.86 - 6.91 (m, 4H), 6.99 (t, J = 9.0, 4H), 7.06 (d, J = 7.5, 2H), 7.22 - 7.30 (m, 6H), 7.40 (s, 2H). Example 123. Preparation of l,6-di-O-(3-fluoro-2-hydroxybenzyl)-2,5-di-O-(4- fluorobenzyι)-D-mannitol (compound no. 137) Step A. 1 ,6-di-O-(2-benzyloxy-3-fluorobenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 74) The alkylation of 3,4-O-isopropylidene-D-mannitol with2-benzyloxy-3-fluorobenzyl chloride was caπied out as described in example 2. The resulting l,6-di-O-(2-benzyloxy-3- fluorobenzyl)-3,4-O-isopropylidene-D-mannitol (54%) was not characterized but reacted with 4- fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane: EtOAc, 1 :1) provided 47% of the desired product. Η NMR (CDC1 3 ): 2.88 (s, 2H), 3.58 - 3.61 (m, 2H), 3.65 - 3.69 (m, 4H), 3.88 (d, J = 6.0, 4.45 - 4.50 (m, 6H), 4.61 (d, J = 11.5. 2H), 5.08 (s, 4H), 6.92 - 6.98 (m, 6H), 7.04 (t, J = 8.5, 2H), 7.09 (d, J = 7.5, 2H), 7.19 - 7.22 (m, 4H), 7.29 - 7.34 (m, 6H), 7.39 (d, J = 7.0, 4H). Step B. l,6-di-O-(3-fluoro-2-hydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH,C1, to yield 83% of the title compound. 'H NMR (CDCI 3 ): 3.70 - 3.74 (m, 6H), 3.94 (d, J = 5.5, 2H), 4.51 (d, J = 12.0, 2H), 4.60 - 4.66 (m, 6H), 6.75 - 6.79 (m, 2H), 6.87 (d, J = 7.0, 2H), 6.94 - 7.03 (m, 6H), 7.24 - 7.27 (m, 4H). Example 124. Preparation of l,6-di-0-(3,5-dihydroxybenzyl)-2,5-di-0-(4-fluorobenzyl)-D- mannitol (compound no. 138) Step A. l,6-di-O-(3,5-dibenzyloxybenzyl)-2.5-di-O-(4-fluorobenzyl)-D-mannitol (compound no. 91) The alkylation of 3,4-O-isopropylidene-D-mannitol with 3,5-dibenzyloxybenzyl chloride was carried out as described in example 2. The resulting l,6-di-O-(3,5-dibenzyloxybenzyl)-3,4-O- isopropylidene-D-mannitol (52%) was not characterized but reacted with 4-fluorobenzyl bromide according to the conditions described in example 4. Purification by flash chromatography (hexane: EtOAc, 1 :1) provided 30%> of the desired product. Η NMR (CDCl j ): 3.07 (t, J = 6.0, 2H), 3.68 (dd, J = 9.5, 5.0, 2H), 3.75 - 3.79 (m, 4H), 3.98 (t, J = 5.5, 2H), 4.50 (s, 4H), 4.57 (d, J = 11.5, 2H), 4.71 (d, J = 11.0, 2H), 5.01 (s, 8H), 6.58 (s, 2H), 6.61 (s, 4H), 6.97 (t, J = 9.0, 4H), 7.27 - 7.43 (m, 24H). Step B. l,6-di-O-(3,5-dihydroxybenzyl)-2,5-di-O-(4-fluorobenzyl)-D-mannitol The product of step A of this example was hydrogenolyzed using 5% palladium on charcoal in methanol and in the presence of pyridine. Filtration and evaporation to dryness left a residue that was purified by flash chromatography eluting with 5% methanol in CH 2 C1 2 gave 87%) of the desired product. 'H NMR (CDCI 3 ): 3.69 - 3.74 (m, 4H), 3.78 (t, J = 6.0, 2H), 3.89 - 3.91 (m, 2H), 3.97 (d, J = 7.0, 2H). 4.43 (s, 4H), 4.60 (d, J = 11.5, 2H), 4.78 (d, J = 1 1.0, 2H), 6.30 (s, 2H), 6.40 (s, 4H), 7.05 (t, J = 7.5, 4H), 7.40 (t, J = 6.0, 4H), 8.16 (s, 4H).

Claims: We claim: 1. A mannitol derivative selected from the group consisting of a compound of formula la: and when a compound of formula la comprises a carboxylic acid group pharmaceutically acceptable salts thereof and when a compound of formula I comprises an amino group pharmaceutically acceptable ammonium salts thereof, wherein R,, R,, R 3 and R 4 are each independently selected from the group consisting of unsubstituted benzyl and benzyl which is substituted by one or more members of the group consisting of -CI, -F, -Br, -I, -CN, -A-CN, -CF 3 , -A-CF 3 , -NO,, R 5 -CO, R 5 -CO-A-, -OCH,C 6 H 5 , - A-S(O) n -R 5 , straight or branched C, to C 6 alkyl, -A-OR 5 , -OR 5 , -NRg R 7 , -A-NR^, -COOR 8 , - A-COOR 8 , -A-NHCOR 8 , -NHCOOR 8 and -A-NHCOOR 8 , wherein n denotes the 0, 1 or 2, A represents an alkylene group having from 1 to 5 carbon atoms, R 5 is selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C, to C 6 alkenyl, C 4 to C π methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyπolyl, pyπolinyl, pyπolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β- carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyπolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl; R <5 and R 7 are each and independently selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C, to C 6 alkenyl, C 4 to C n methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyπolyl, pyπolirϊyl, pyπolidim1, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyπolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl or R 6 and R 7 together with the nitrogen atom to which they are bonded represent a saturated or unsaturated heterocyclic group of formula wherein Ya and Za each independently denotes a normal hydrocarbon chain comprising 1 to 3 carbon atoms, Xa denotes O and n " denotes 0 or 1, provided that when n' denotes 1 Ya and Za cannot both comprise 3 carbon atoms at the same time and that when n' denotes 0 Ya and Za are bonded directly together, and R 8 is selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C, to C 6 alkenyl, C 4 to C u methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyπolyl, pyπolinyl, pyπolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β- carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyπolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl. 2. A compound of formula la as defined in claim 1 wherein R, and R 4 are the same and each denote an unsubstituted benzyl, where R, and R 3 are the same and each denote a benzyl group of formula wherein Rj is selected from the group consisting of -CI, -F, -Br, -CN, -CF 3 , -NO 2 , -CHO, - OCH 2 C 6 H 5 , -CH 3 , -NH 2 , -OH, -COOCH 3 , -COOH, -CH,NH 2 , -CONH 2 , -NH-tert- butyloxycarbonyl and -NHCOOR 10 wherein R 10 is -H or tert-butyl. 3. A compound of formula la as defined in claim 1 wherein R, and R 3 are the same and each denote an unsubstituted benzyl, where R j and R 4 are the same and each denote a benzyl group of formula wherein R u is selected from the group consisting of -CI, -F, -Br, -CN, -CF 3 , -NO 2 , -CH 2 OH, CH 3 , -NH 2 , -COOR 12 , -COOH wherein R 12 is methyl or iso-butyl. 4. A compound of formula la as defined in claim 1 wherein R ] and R 4 are the same and each denote a benzyl group of formula wherein R 14 is selected from the group consisting of -F, -CN, CF 3 , -OH, -CH 3 and OCH,C 6 H 5 and wherein R, and R 3 are the same and each denote a benzyl group of formula wherein R 15 is selected from the group consisting of -F, -CN, -CF 3 , -OH and CH 3 . 5. A compound of formula la in claim 1 wherein R j denotes a substituted benzyl group of formula and wherein R,, R 3 and R 4 each denote an unsubstituted benzyl group. 6. A compound of formula la in claim 1 wherein R 2 and R 3 each denotes a substituted benzyl group of formula and wherein R,and R 4 each denote an unsubstituted benzyl group. 7. A compound of formula la in claim 1 wherein R, and R 4 denote a substituted benzyl group of formula and wherein R 2 and R 3 each denote an unsubstituted benzyl group. A compound of formula la in claim 1 wherein R, and R 3 denote a substituted benzyl group of formula and wherein R x and R 4 each denote a benzyl group of formula A compound of formula la in claim 1 wherein R 2 and R 3 denote a substituted benzyl group of formula and wherein Ri and R 4 each denote a benzyl group of formula 10. A compound of formula la in claim 1 wherein R 3 denotes a benzyl group, R, R 2 and R 4 each denotes a benzyl group of formula 11. A compound of formula la as defined in claim 1 wherein R ls R 2 , R 3 and R 4 are each independently selected from the group consisting of unsubstituted benzyl and benzyl which is substituted by one or more members of the group consisting of F and -OH, and provided that at least one of R,, R 2 , R 3 and R 4 is benzyl which is substituted by one or more members of the group consisting of F and -OH. 12. A compound of formula la as defined in claim 1 wherein R 2 and R 3 are the same and each represents a benzyl group of formula and wherein R, and R 4 are the same or different and each represents a benzyl group of fc/rmula wherein n is 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH 3 . 13. A compound of formula la as defined in claim 12 wherein R, and R 4 are the same. 14. A compound of formula la as defined in claim 12 wherein K and R 4 each represents a benzyl group of formula 15. A compound of formula la as defined in claim 12 wherein Rj and R 4 each represents a benzyl group of formula 16. A compound of formula la as defined in claim 12 wherein K λ and R 4 each represents a benzyl group of formula 17. A compound of formula la as defined in claim 12 wherein R { and R 4 each represents a benzyl group of formula 18. A compound of formula la as defined in claim 12 wherein R ! and R 4 each represents a benzyl group of formula 19. A compound of formula la as defined in claim 12 wherein R, and R 4 each represents a benzyl group of formula 20. A compound of formula la as defined in claim 12 wherein R, and R 4 each represents a benzyl group of formula 21. A compound of formula la as defined in claim 1 wherein R 2 and R 3 are the same and each represents a benzyl group of formula wherein is an unsubstituted benzyl group and wherein R 4 represents a benzyl group of formula wherein n is 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH 3 . 22. A compound of formula la as defined in claim 21 wherein R 4 represents a benzyl group of formula 23. A compound of formula la as defined in claim 1 wherein R j and R 4 are the same and each represents a benzyl group of formula and wherein R 2 and R 3 are the same or different and each represents a benzyl group of formula wherein n is 0, 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH 3 24. A compound of formula la as defined in claim 23 wherein R 2 and R 3 are the same. 25. A compound of formula la as defined in claim 24 wherein R 2 and R 3 each represents a benzyl group of formula 26. A compound of formula la as defined in claim 23 wherein R 2 represents an insubstituted benzyl group and wherein R 3 represents a benzyl group of formula 27. A compound of formula la as defined in claim 23 wherein R 2 and R 3 each represents a benzyl group of formula 28. A compound of formula la as defined in claim 24 wherein R 3 represents a benzyl group of formula 29. A compovmd of formula la as defined in claim 28 wherein R, represents a benzyl group of formula 30. A compound of formula la as defined in claim 28 wherein R 2 represents a benzyl group of formula 31. A compound of formula 1 a as defined in claim 28 wherein R 3 represents a benzyl group of formula 32. A compound of formula la as defined in claim 1 wherein j represents a benzyl group of formula wherein R 2 represents a benzyl group of formula wherein R 3 represents an unsubstituted benzyl group and wherein R 4 represents a benzyl group of formula wherein n is 1 or 2 and Z is selected from the group consisting of -OH, F, -OCH 3 and -CH 3 A compound of formula la as defined in claim 32 wherein R 4 represents a benzyl group of formula 34. A compound of formula la as defined in claim 32 wherein R 4 represents a benzyl group of formula 35. A compound of formula la as defined in claim 32 wherein R 4 represents a benzyl group of formula 36. A compound of formula la as defined in claim 11 wherein λ and R 4 are the same and each represents a benzyl group of formula wherein R, is an unsubstituted benzyl group and wherein R 3 represents a benzyl group of formula 37. A compound of formula la as defined in claim 11 wherein R 2 and R 3 are the same and each represents a benzyl group of formula wherein R, is an unsubstituted benzyl group and wherein R 4 represents a benzyl group of formula 38. A compound of formula la as defined in claim 11 wherein R 1; R 2 and R 3 each represents an unsubstituted benzyl group and wherein R 4 represents a benzyl group of formula 39. A pharmaceutical composition comprising a pharmaceutically acceptable carrier and a pharmaceutically effective amount of at least one compound of formula la as defined in claim 1. 40. A mannitol derivative selected from the group consisting of a compound of formula 1 : and when a compound of formula la comprises a carboxylic acid group pharmaceutically acceptable salts thereof and when a compound of formula I comprises an amino group pharmaceutically acceptable ammonium salts thereof, wherein R l5 R 2 , R 3 and R 4 are each independently selected from the group consisting of to C 5 alkyl, -(C, to C 5 alkylene) m - Ar -(OO)-(Cι to C 5 alkylene) m - Ar -(OS)-(Cι to C 5 alkylene) m - Ar -(C=O)-O-CH 2 - Ar -(C=S)-S-CH 2 - Ar and -(C=S)-S-CH 3 wherein m denotes 0 or 1 and each Ar is independently selected from the group consisting of allyl, vinyl, styryl, cyclopropyl, naphthyl, pyridyl, thienyl, unsubstituted phenyl and phenyl which is substituted by one or more members of the group consisting of -CI, -F, -Br, -I, -CN, -A- CN, -CF 3 , -A-CF 3 , -NO 2 , R 5 -CO, R 5 -CO-A-, -OCH 2 C 6 H 5 , -A-S(O)n-R 5 , straight or branched C to C 6 alkyl, -A-OR 5 , -OR 5 , -NR^ R 7 , -A-NILR 7 , -COOR 8 , -A-COOR 8 , -A-NHCOR 8 , -NHCOORg and -A-NHCOOR 8 , wherein n denotes the 0, 1 or 2, A represents an alkylene group having from 1 to 5 carbon atoms, R 5 is selected from the group consisting of H and straight or branched C l to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C n methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β- carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl; Rg and R 7 are each and independently selected from the group consisting of H and straight or branched C, to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C n methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β-carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl or R^ and R 7 together with the nitrogen atom to which they are bonded represent a saturated or unsaturated heterocyclic group of formula wherein Ya and Za each independently denotes a normal hydrocarbon chain comprising 1 to 3 carbon atoms, Xa denotes O and n' denotes 0 or 1, provided that when n' denotes 1 Ya and Za cannot both comprise 3 carbon atoms at the same time and that when n' denotes 0 Ya and Za are bonded directly together and R 8 is selected from the group consisting of H and straight or branched C t to C 6 alkyl, straight or branched C 2 to C 6 alkenyl, C 4 to C n methylcycloalkyl, phenyl, mono- or poly-substituted phenyl, benzimidazolyl, imidazolyl, imidazolinyl, imidazolidinyl, quinolyl, isoquinolyl, indolyl, pyridyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl, morpholinyl, β- carbolinyl, tetrazolyl, thiazolidinyl, benzofuranyl, thiamorpholinyl, benzoxazolyl, oxopiperidinyl, oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxazolyl, tetrahydropyranyl, tetrahydrofuranyl, thiadiazolyl, thiadiazinyl, benzodioxolyl, thiophenyl, tetrahydrothiophenyl, nicoticoyl, morpholinecarbodithioyl and sulfolanyl.

Inventors: BOUZIDE ABDERRAHIM, SAUVE GILLES, BOUZIDE, ABDERRAHIM, SAUVE, GILLES
Applicants: PHARMACOR INC, PHARMACOR INC.
Application year: 2000
Main classification: C07C43
IPC codes: A61P31, C07C43, C07C45, C07C47, C07C69, C07C205, C07C217, C07C235, C07C255, C07C271, C07C323, C07C329, C07D213, C07D333