Patent Application: US-44124095-A

Abstract:
the present invention is a compound having the structure where : anthracycline is doxorubicin , daunorubicin or a derivative thereof ; n is the 3 ′ nitrogen of daunosamine ; r a is h or alkyl ; x is , o , s , cr c 2 or nr c where r c is h or alkyl ; r b is alkyl or aryl ; n is 1 to 6 ; and m is 0 to 6 . r a and r c are preferably h , methyl , ethyl , propyl or butyl , although other alkyl substituents are usable . r b is alkyl or aryl . the compound of the present invention as described above is activatable in vivo by esterases and spontaneous dehydration to form an aldehyde . the aldehyde may couple to nucleophiles of intracellular macromolecules . the compounds of the present invention are cytotoxically effective in the inhibition of human myeloma cells .

Description:
the anthracycline antibiotic doxorubicin is effective in the palliative management of a wide variety of human malignancies 1 . however , the clinical utility of doxorubicin is limited by a number of problems , including intrinsic and acquired drug resistance and dose - dependent cardiomyopathy . numerous analogues have been synthesized in an attempt to overcome these shortcomings . 2 - 4 a series of derivatives in which the 3 ′- amino group of the daunosamine sugar is replaced with a morpholino substituent has been reported by acton and coworkers . 5 - 7 one of these analogues , 3 ′- deamino - 31 -( 3 - cyano - 4 - morpholinyl )- adriamycin ( mra - cn ) is 100 to 1000 times more cytotoxic than doxorubicin in vitro 7 - 10 and in vivo 6 , 11 and retains its potency against several tumor cell lines with acquired resistance to doxorubicin . 9 , 12 , 13 the compounds of the present invention , bis ( acyloxy ) acetals of an anthracycline such as doxorubicin ( adriamycin ), for example , are designed to be relatively stable , non - toxic but subject to activation by in vivo enzymes ( esterases ) to form an aldehyde hydrate from the bis ( acyloxy ) acetal . this aldehyde hydrate is labile and eliminates water to form an aldehyde . by varying the composition of the anthracycline bisacyloxy - bearing side chain , many different analogues are possible , all of which will be activatable at various rates by endogenous esterases and spontaneous decompositions to form active anthracycline aldehyde derivatives . it is possible to vary the composition of the side chain in both composition and length to prepare a series of such analogues having desired specificities and / or non - toxicities toward particular biological sites . the side chain connecting the anthracycline and the bis acyloxy substituent will comprise at least one methylene ( ch 2 ) group and may contain up to 9 such groups . when more than one methylene group is present there may be an additional spacer group such as o , s or nr a where r a is h or alkyl with usually less than 5 carbon atoms , depending upon the particular properties desired . a series of analogues , 1 , ( fig1 ) bearing alkylating or latent alkylating substituents , r , on the 3 ′- position of the daunosamine sugar were prepared . these compounds were designed on the premise that alkylating anthracyclines should bind covalently to critical intracellular macromolecules and overcome resistance to doxorubicin arising from reduced cellular drug accumulation . however , in growth inhibitory studies against mouse ( l1210 and p388 ) and human ( uterine sarcoma , myelocytic ) tumor cells in vitro , these analogues were 5 - to 100 - fold less potent than the parent compound ( doxorubicin ). these analogs nevertheless did retain their cytotoxic activity against variants of these same cell lines which were resistant to doxorubicin . to identify new alkylating anthracyclines with increased potency , a series of doxorubicin analogues was synthesized in which the 3 +- amino group is substituted with a latent alkanal or heteroalkanal group . a rationale for the design of these compounds was that : ( a ) the latent alkanal or heteroalkanal groups would be converted to the corresponding free aldehydes when the drugs were placed in a biological medium ( such as cells or whole organisms ), and ( b ) the liberated free aldehydes would react with nucleophiles ( such as amino or sulfhydryl groups ) proximate to the dna drug - binding site to form covalent adducts . as a consequence , drug egress from the cell should be inhibited . because of the intrinsic chemical reactivity of free aldehydes , the alkanal ( or heteroalkanal ) groups were introduced into the doxorubicin molecule in latentiated form . bis ( acyloxy ) groups were selected for this purpose . the general structure of the new doxorubicin analogues is shown in fig2 where the anthracycline is doxorubicin or daunorubicin . additionally , the acyloxy group may be varied . for example , the acyloxy group may be acetate , propionate , butyrate ( n or t ) or even benzoate or substituted benzoate . the acyloxy substituent may also be varied to control the rate of drug activation resulting from ester hydrolysis . for example , certain sterically hindered ester groups may be hydrolyzed much less rapidly than a simpler substituent such as acetoxy . the mechanism for regeneration of the free aldehyde is illustrated in fig3 with respect to compound 2a ( fig2 n = 2 , m = 1 , x = cr c 2 where r c is h , r b = ch 3 and r a = h ). in the presence of carboxylate esterases , enzymes that are ubiquitous in tissue , and which show low substrate specificity , compound 2a can be hydrolyzed to the corresponding aldehyde hydrate , 3a . elimination of water from 3a generates the free aldehyde , 4a . the aldehyde group can then react with a nucleophile such as one on a macromolecule proximate to , or within , a dna - binding site to form a potential covalent drug - dna adduct , 5a . apart from recent studies by the inventors &# 39 ; laboratory with cyclophosphamide metabolites ( see u . s . pat . no . 4 , 841 , 085 and aldophosphamide bis ( acetoxy ) acetal and structural analogues . j . med . chem ., in press , 1990 , for example ) this approach to the bioreversible latentiation of aldehydes has not been described previously and has not at all been described before for anthracycline derivatives . an important aspect of this strategy is that by judicious selection of the acyloxy groups , it should be possible to modify the lipophilicity and aqueous solubility of these analogues . moreover , since these compounds are designed to be activated by carboxylate esterases ( enzymes present in all cells ), the acyloxy masking groups can be altered to control the rate at which the active “ alkylating ” anthracyclines are formed . a number of compounds having the general structure 2 have been prepared . these were synthesized by condensing doxorubicin with a dialdehyde monoacetal then reducing the intermediate imine with nabh 3 cn . the overall synthetic strategy can be exemplified with respect to 2a by as schematically illustrated in fig4 . to the best of applicants &# 39 ; knowledge , dialdehyde monoacetals such as 10 have not been reported previously . [ these should be versatile synthetons in organic synthesis since the acetal ester groups can be cleaved under extremely mild conditions ( weak base or esterase activity )]. condensation of 10 with doxorubicin , 11 , in the presence of nacnbh 3 generated 2a directly in & gt ; 50 % yield . evidence for the structure of 2a was obtained by 1 h and cosy nmr , and by mass spectrometry . the compound is freely soluble in aqueous media and is stable at neutral ph . to investigate structure - activity relationships for this class of compounds , the analogs ( based upon structure 2 of fig2 ) shown in table 1 have been prepared . this strategy obviously may be readily extended to the synthesis of a series of analogues where , e . g ., x = o , s , nr c or cr c 2 where r c is h or alkyl ; n = 1 - 6 ; m = 0 - 6 ; r a = h , ch 3 , c 2 h 5 , c 3 h 7 or other hydrocarbons ( c x h 2 ×+ 1 ); and r b 32 ch 3 , c 2 h 5 , c 3 h 7 , or c ( ch 3 ) 3 . while hydrochloride salts have been prepared , it is well known to utilize other pharmaceutically acceptable acids in place of hydrochloric acid to make numerous pharmaceutically acceptable salts . nuclear magnetic resonance spectra ( 1 h and 13 c ) were recorded at ambient temperature on an ibm - bruker model nr / 200 af spectrometer in the fourier transform mode in cdcl 3 with tetramethylsilane as an internal reference . chemical shifts ( o ) are reported in parts per million ( ppm ) and coupling constants ( j ) in hertz units . specialist nmr techniques used for structural assignment include : off - resonance decoupling plus single frequency , selective heteronuclear decoupling , homonuclear shift - correlated 2d - nmr ( cosy ), homonuclear shift - correlated 2d - nmr with a delay period to emphasize long range or small coupling ( cosylr ), and heteronuclear shift - correlated 2d - nmr using polarization transfer from 1 h to 13 c via j ch ( xh - corr ). mass spectral analyses were conducted at texms , 15701 west hardy road , houston , tex . using an atmospheric pressure desorption technique . all chemical reactions were carried out in dry glassware and were protected from atmospheric moisture . solvents were dried over freshly activated ( 300 ° c ./ 1 h ) molecular sieves ( type 4 a ). evaporations were carried out on a rotary evaporator under aspirator vacuum at a bath temperature of & lt ; 25 ° c . the homogeneity of the products was determined by ascending tlc on silica - coated glass plates ( silica gel 60 f 254 , merck ) using mixtures of chcl 3 — meoh as the eluting solvent . preparative separations were performed on thick layers ( 20 cm × 20 cm × 2 mm ) of the same adsorbent or by column chromatography on silica gel ( merck , 230 - 400 mesh ) using mixtures of chcl 3 — meoh as eluent . a solution of the jones reagent in acetone ( 10 ml , 2 . 67 m ) was added , dropwise , with stirring over 10 min to a solution of 5 - hexen - 1 - ol ( 6 ) ( 2 ml , 1 . 67 g , 17 mmol ) in acetone ( 5 ml ) at 0 ° c . the reaction mixture was maintained at 5 ° c . for 1 h . saturated nahco 3 solution was added to bring the ph to 7 . 0 and the mixture was extracted with chcl 3 ( 3 × 20 ml ). the combined extracts were washed with h 2 o ( 3 × 20 ml ), and dried over anhydrous na 2 so 4 . the solvent was evaporated to give a crude product , which was then purified by filtering - column chromatography on silica gel ( 98 : 2 chcl 3 / meoh ) to give 0 . 98 g ( 10 mmol ) of pure 5 - hexen - 1 - al ( 8 ) as a colorless oil . yield 59 %. 1 h nmr [ chemical shift ( o ), multiplicity , coupling constant ( hz ), number of protons , atom ]: 9 . 71 ( t , j = 1 hz , 1 h , h - 1 ), 5 . 75 ( m , 1 h , h - 5 ), 5 . 04 ( m , 2 h , h - 6 ), 2 . 45 ( m , 2 h , h - 2 ), 2 . 08 ( m , 2 h , h - 4 ), 1 . 72 ( m , 2 h , h - 3 ). 13 c nmr ( ppm , atom ): 201 . 95 ( c - 1 ), 137 . 18 ( c - 5 ), 115 . 07 ( c - 6 ), 42 . 67 ( c - 2 ), 32 . 55 ( c - 4 ), 20 . 75 ( c - 3 ). a solution of 5 - hexen - 1 - ol ( 6 ) ( 2 ml , 1 . 67 g , 17 mmol ) in ch 2 cl 2 ( 5 ml ) was added in one portion to a stirred solution of pyridinium chlorochromate 16 ( 5 . 5 g , 25 . 5 mmol ) in anhydrous ch 2 cl 2 ( 35 ml ) contained in a 100 ml round bottomed flask fitted with a reflux condenser . after 2 . 5 h at ambient temperature , dry ether ( 40 ml ) was added . the organic supernatant was decanted and the residual black gum was triturated with anhydrous ether ( 3 × 10 ml ) until a black granular solid remained . the organic extracts were combined , filtered through a short pad of florisil , then concentrated under reduced pressure . the residual liquid was passed through a short vigreaux column to give 1 . 37 g of pure 5 - hexen - 1 - al ( 83 ( 14 mmol , 82 %). the spectral properties of the compound were identical with that of the product obtained by method a . 4a powdered molecular sieves ( 500 mg / mmol , 8 . 5 g ) was added to a solution of 5 - hexen - 1 - ol ( 6 ) ( 2 ml , 1 . 67 g , 17 mmol ) and n - methylmorpholine n - oxide ( 1 . 5 eq ., 25 . 6 mmol , 3 . 4 g ) in ch 2 cl 2 ( 35 ml ). the mixture was stirred for 10 min at room temperature under a nitrogen atmosphere then tetrapropyl - ammonium perruthenate ( tpap ) 17 ( 0 . 30 g , 0 . 85 mmol , 5 mol %) was added in one portion . the initially green mixture progressively darkened . the reaction was completed after 2 h at room temperature ( as evidenced by tlc ), ch 2 cl 2 ( 35 ml ) was added and the mixture was passed first through a short pad of filter agent , ( celite ). the filtrate was evaporated and the residual crude was purified by filtering - column chromatography on silica gel ( 98 : 2 , chcl 3 / meoh ) to afford 1 . 47 g of pure 5 - hexen - 1 - al ( 8 ) ( 15 mmol , 88 %). the spectral properties of the compound were identical with that of the product obtained by method a . since the tpap oxidation procedure gave the best yields and was the most convenient , it was used for all subsequent procedures for the preparation of aldehydes from the corresponding alcohols . a : 4 - penten - 1 - ol ( 12 ) ( 1 . 76 ml , 1 . 46 g , 17 mmol ) as desribed for 5 - hexen - 1 - al ( 8 ), method c . the total yield of the desired aldehyde ( 13 ) was 91 %, ( 15 . 58 mmol , 1 . 31 g ). 1 h nmr : 9 . 91 ( t , j = 1 hz , 1 h , h - 1 ), 5 . 80 ( m , 1 h , h - 4 ), 5 . 21 ( m , 2 h , h - 5 ), 2 . 12 ( m , 2 h , h - 2 ), 1 . 95 ( m , 2 h , h - 3 ). 13 c nmr : 200 . 28 ( c - 1 ), 137 . 61 ( c 4 ), 114 . 96 ( c - 5 ), 32 . 80 ( c - 2 ), 32 . 21 ( c - 3 ). bi 5 - hexen - 1 , 2 - diol ( 2 . 24 ml , 2 . 2 g , 18 . 9 mmol ) was added slowly , with stirring , over 10 min to a solution of naio 4 ( 4 . 1 g ) in water ( 45 ml ) under ice cooling , and then left at room temperature for 2 h . ethanol ( 30 ml ) was added and the mixture was filtered to remove precipitated sodium salts , and concentrated . chloroform ( 50 ml ) and h 2 o ( 20 ml ) were added , and the organic layer was separated , dried , filtered , and evaporated to dryness . the residue was chromatographed on silica gel ( 96 : 4 chcl 3 / meoh ) to give 4 - penten - 1 - al ( 13 ) as a colorless liquid ( 1 . 2 g , 14 . 2 mmol , 75 %). the spectral properties of the compound were identical with that of the product obtained by method a . this product was prepared from 6 - hepten - 1 - ol ( 17 ) ( 1 . 9 g , 17 mmol ), as described for 5 - hexen - 1 - al ( 8 ), method c . the total yield of the desired ( 18 ) was 90 %, ( 15 . 3 mmol , 1 . 72 g ). 1 h nmr : 9 . 62 ( s , 1 h , h - 1 ), 5 . 83 ( m , 1 h , h - 6 ), 4 . 92 ( m , 2 h , h - 7 ), 2 . 41 ( t , 2 h , j = 7 . 1 hz , h - 2 ), 1 . 74 ( m , 2 h , h - 3 ), 1 . 51 ( m , 2 h , h - 5 ), 1 . 35 ( m , 6 h , h - 4 ). 13 c nmr : 202 . 51 ( c - 1 ), 138 . 04 ( c - 6 ), 114 . 67 ( c - 7 ), 43 . 44 ( c - 2 ), 33 . 43 ( c - 5 ), 28 . 13 ( c - 3 ), 24 . 81 ( c - 4 ). this product was prepared from 8 - nonen - 1 - ol 18 ( 21 ) ( 2 . 4 g , 17 mmol ) as desribed for 5 - hexen - 1 - al ( 8 ), method c . the residue was subjected to a column chromatography on silica gel ( 98 : 2 chcl3 / meoh ), yielding 2 . 12 g as a syrup ( 15 . 13 mmol , 89 %) of ( 22 ). 1 h nmr : 9 . 65 ( s , 1 h , h - 1 ), 5 . 72 ( m , 1 h , h - 8 ), 4 . 95 ( m , 2 h , h - 9 ), 2 . 43 ( t , 2 h , j = 5 hz , h - 2 ), 2 . 12 ( m , 2 h , h - 7 ), 1 . 54 ( m , 2 h , h - 3 ), 1 . 33 ( m , 6 h , h - 4 , h - 5 , h - 6 ). 13 c nmr : 200 . 54 ( c - 1 ), 138 . 82 ( c - 8 ), 114 . 11 ( c - 9 ), 35 . 01 ( c - 2 ), 34 . 24 ( c - 7 ), 28 . 83 ( c - 3 ), 28 . 74 ( c - 6 ), 23 . 92 ( c - 4 ), 23 . 24 ( c - 5 ). a solution of allyl alcohol ( 30 ml , 25 . 6 g , 0 . 44 mol ), monochloroacetic acid ( 3 g , 0 . 032 mol ), and sodium hydroxide ( 1 . 27 g , 0 . 032 mol ) in h 2 o ( 5 ml ) was added dropwise , with stirring over 10 min to acrolein ( 80 ml , 1 . 2 mol ) contained in a 250 ml flask . acetic acid ( 12 ml , 0 . 21 mol ) was added and the reaction mixture was maintained at 40 ° c . for 40 h . after cooling to room temperature , the mixture was washed with h 2 o ( 50 ml × 3 ), and the organic layer was dried over anhydrous na 2 so 4 . the solution was concentrated under aspirator vacuum at 40 ° c . to remove volatile by - products . the residual viscous oil was purified by column chromatography on silica gel using ch 2 cl 2 as a eluent to give 34 . 2 g of ( 25 ) ( 0 . 3 mol ) as a colorless oil . yield , 69 %. 1 h nmr : 9 . 82 ( t , 1 h , j = 1 hz , h - 1 ), 5 . 82 ( m , 1 h , h - 2 ′), 5 . 21 ( m , 2 h , h - 3 ′), 3 . 93 ( dt , 2 h , j = 3 , 1 hz , h - 1 ′), 3 . 82 ( t , 2 h , j = 4 hz , h - 3 ), 2 . 61 ( dt , 2 h , j = 4 , 1 hz , h - 2 ). 13 c nmr : 202 . 12 ( c - 1 ), 134 . 24 ( c - 2 ′), 116 . 24 ( c - 3 ′), 71 . 43 ( c - 1 ′), 64 . 34 ( c - 3 ), 34 . 12 ( c - 2 ). 5 - hexen - 1 - al ( 8 ) ( 5 g , 5 . 9 ml , 50 . 9 mmol ) was added dropwise , with stirring over 5 min at ambient temperature to a solution of acetic anhydride ( 3 ml , 31 mmol ) and bf 3 . et 2 o ( 0 . 5 ml ) in anhydrous et 2 o ( 10 ml ). the reaction mixture was stirred for 10 min , then washed successively with 25 % naoac solution ( 20 ml ) and h 2 o ( 25 ml × 2 ), and dried over anhydrous na 2 so 4 . the ether was evaporated and the residue was distilled to give the diacetoxy acetal ( 9 ) ( 9 . 6 g , 48 mmol , 94 %). the product was used in subsequent reactions without further purification . 1 h nmr : 6 . 83 ( t , 1 h , j = 5 hz , h - 1 ), 5 . 58 ( m , 1 h , h - 5 ), 5 . 02 ( m , 2 h , h - 6 ), 2 . 12 ( s , 6 h , ch 3 ), 2 . 05 ( m , 2 h , h - 2 ), 1 . 85 ( m , 2 h , h - 4 ), 1 . 50 ( m , 2 h , h - 3 ). 13 c nmr : 168 . 42 ( c och 3 ), 137 . 43 ( c - 5 ), 114 . 81 ( c - 6 ), 89 . 92 ( c - 1 ), 32 . 82 ( c - 2 ), 32 . 14 ( c - 4 ), 22 . 23 ( c - 3 ), 20 . 32 ( c h 3 ). the compound was prepared from 4 - penten - 1 - al ( 13 ) ( 6 . 7 g , 7 . 8 ml , 80 mmol ), acetic anhydride ( 5 . 7 ml , 6 . 13 g , 60 mmol ) and bf 3 . et 2 o ( 0 . 2 ml ) in et 2 o ( 6 ml ) as described for ( 9 ). after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 97 : 3 chcl 3 / meoh ) to give the diacetoxy acetal ( 14 ) ( 14 g , 75 . 2 mmol , 94 %) 1 h nmr : 6 . 85 ( t , 1 h , h - 1 , j = 5 hz ), 5 . 74 ( m , 1 h , h - 4 ), 4 . 95 ( m , 2 h , h - 5 ), 2 . 05 ( m , 2 h , h - 2 ), 2 . 03 ( s , 6 h , ch 3ac . ), 1 . 85 ( m , 2 h , h - 3 ). 13 c nmr : 168 . 75 ( c och 3 ), 137 . 64 ( c - 4 ), 115 . 01 ( c - 5 ), 89 . 85 ( c - 1 ), 32 . 96 ( c - 2 ), 32 . 17 ( c - 3 ), 20 . 24 ( c h 3 ). the compound was prepared from 6 - heptenal ( 18 ) ( 4 g , 4 . 7 ml , 35 mmol ), acetic anhydride ( 2 . 8 ml , 3 . 1 g , 30 mmol ) and bf 3 . et 2 o ( 0 . 2 ml ) in et 2 o ( 5 ml ) as described for ( 9 ). after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 97 : 3 chcl 3 / meoh ) to give the diacetoxy acetal ( 19 ) ( 7 . 14 g , 33 . 3 mmol , 95 %) 1 h nmr : 6 . 87 ( t , j = 5 hz , 1 h , h - 1 ), 5 . 83 ( m , 1 h , h - 6 ), 4 . 98 ( m , 2 h , h - 7 ), 2 . 15 ( dt , j = 5 , 1 hz , 3 h , h - 2 ), 2 . 02 ( s , 6 h , c h 3ac ), 1 . 90 ( m , 2 h , h - 5 ), 1 . 64 ( m , 4 h , h - 3 , h - 4 ). 13 c nmr : 168 . 54 ( c och 3 ), 137 . 93 ( c - 6 ), 114 . 92 ( c - 7 ), 89 . 86 ( c - 1 ), 33 . 43 ( c - 2 ), 33 . 14 ( c - 5 ), 24 . 52 ( c - 3 ), 21 . 21 ( c - 4 ), 20 . 22 ( c h 3 ). the compound was prepared from 2 , 2 - dimethyl - 4 - penten - 1 - al ( 28 ) ( 3 ml , 2 . 5 g , 22 mmol ) acetic anhydride ( 1 . 4 ml , 1 . 56 g , 15 mmol ) and bf 3 . et 2 o ( 0 . 2 ml ) in et 2 o ( 5 ml ) as described for ( 9 ). after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 96 : 4 chcl 3 / meoh ) to give the diacetoxy acetal ( 29 ) ( 4 . 44 g , 20 . 7 mmol , 94 %). 1 h nmr : 6 . 52 ( s , 1 h , h - 1 ), 5 . 75 ( m , 1 h , h - 4 ), 4 . 95 ( m , 2 h , h - 5 ), 2 . 05 ( s , 6 h , c h 3ac ), 2 . 02 ( m , 2 h , h - 3 ), 1 . 85 ( s , 6 h , ch 3 ) 13 c nmr : 168 . 63 ( c och 3 ), 133 . 46 ( c - 4 ), 117 . 65 ( c - 5 ), 93 . 55 ( c - 1 ), 41 . 43 ( c - 3 ), 37 . 42 ( c - 2 ), 21 . 01 ( c h 3 ), 20 . 34 ( c h 3ac ) the compound was prepared from 8 - nonen - 1 - al ( 22 ) ( 8 . 3 ml , 7 g , 50 mmol ), acetic anhydride ( 3 . 8 ml , 4 g , 40 mmol ) and bf 3 . et 2 o ( 0 . 2 ml ) in et 2 o ( 7 ml ) as described for ( 9 ). after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 97 : 3 chcl 3 / meoh ) to give the diacetoxy acetal ( 23 ) ( 11 . 75 g , 48 . 5 mmol , 97 %). 1 h nmr : 6 . 82 ( t , 1 h , j = 5 . 6 hz , h - 1 ), 5 . 75 ( m , 1 h , h - 8 ), 4 . 95 ( m , 2 h , h - 9 ), 2 . 02 ( s , 6 h , ch 3ac . ), 1 . 98 ( m , 2 h , h - 7 ), 1 . 75 ( m , 2 h , h - 2 ), 1 . 54 ( m , 2 h , h - 4 ), 1 . 35 ( m , 6 h , h - 6 , h - 5 , h - 3 ). 13 c nmr : 168 . 84 ( c och 3 ), 138 . 83 ( c - 8 ), 114 . 12 ( c - 9 ), 90 . 43 ( c - 1 ), 34 . 92 ( c - 2 ), 34 . 15 ( c - 7 ), 28 . 84 ( c - 3 ), 28 . 71 ( c - 6 ), 23 . 84 ( c - 4 ), 23 . 21 ( c - 5 ), 20 . 64 ( c h 3 ). the compound was prepared from 3 -( allyloxy ) propionaldehyde ( 25 ) ( 5 . 2 ml , 5 g , 44 mmol ), acetic anhydride ( 2 . 4 ml , 25 mmol ) and bf 3 / et 2 o ( 0 . 2 ml ) in et 2 o ( 5 ml ) as described for ( 9 ). after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 96 : 4 chcl 3 / meoh ) to give the diacetoxy acetal ( 26 ) ( 8 . 94 g , 41 . 4 mmol , 94 %). 1 h nmr : 6 . 92 ( t , 1 h , j = 4 hz , h - 1 ), 5 . 85 ( m , 1 h , h - 2 ′), 5 . 23 ( m , 2 h , h - 3 ′), 3 . 95 ( dt , 2 h , j = 3 , 1 hz , h - 1 ′), 3 . 44 ( t , 2 h , j = 4 hz , h - 3 ), 2 . 01 ( s , 6 h , c h 3ac ), 1 . 95 ( dt , 2 h , j = 4 , 2 hz , h - 2 ). 13 c nmr : 168 . 02 ( c och3 ), 134 . 44 ( c - 2 ′), 116 . 43 ( c - 3 ′), 88 . 42 ( c - 1 ), 71 . 41 ( c - 1 ′), 64 . 76 ( c - 3 ), 33 . 25 ( c - 2 ), 20 . 26 ( c h 3 ). the compound was prepared from acrolein ( 6 ml , 5 g , 90 mmol ), acetic anhydride ( 5 . 7 ml , 6 . 13 g , 60 mmol ) and bf 3 / et 2 o ( 0 . 25 ml ) in et 2 o ( 5 ml ) as described for ( 9 ) after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 97 : 3 chcl 3 / meoh ) to give the diacetoxy acetal ( 31 ) ( 13 . 7 g , 86 . 4 mmol , 96 %). 1 h nmr : 7 . 14 ( d , j = 7 hz , 1 h , h - 1 ), 5 . 85 ( m , 1 h , h - 2 ), 5 . 45 ( m , 2 h , h - 3 ), 2 . 05 ( s , 6 h , c h 3 ). 13 c nmr : 168 . 15 ( c och 3 ), 131 . 12 ( c - 2 ), 119 . 44 ( c - 3 ), 88 . 76 ( c - 1 ), 20 . 38 ( c h 3 ). a solution of 5 - hexen - 1 , 1 - diacetate ( 9 ) ( 5 g , 3 . 5 ml , 25 mmol ) in ch 2 cl 2 ( 5 ml ) was placed in a long cylindrical gas absorption vessel with an inlet dispersion tube extending to the base . the vessal was cooled to − 70 ° c . in a dry ice / acetone mixture , and ozone was introduced . ozonization was continued until all of the compound had reacted ( blue color due to the formation of the ozonide ), approximately 20 min . methyl sulfide ( 7 . 25 ml , 0 . 1 mol , 4 equivalents ) was added to the blue solution of ozonide and the mixture was stirred overnight to reduce the ozonide to the corresponding aldehyde . the excess methyl sulfide was evaporated , and the residue was subjected to a column chromatography on silica gel ( ch 2 cl 2 ) giving aldehyde ( 10 ) ( 4 . 29 g , 21 . 25 mmol , 85 %) as a syrup . 1 h nmr : 9 . 83 ( t , 1 h , j = 1 hz , h - 5 ), 6 . 75 ( t , 1 h , j = 5 hz , h - 1 ), 2 . 66 ( dt , 2 h , j = 5 . 5 , 1 hz , h - 4 ), 2 . 14 ( s , 6 h , ch 3 ), 2 . 05 ( m , 2 h , h - 2 ), 1 . 85 ( m , 2 h , h - 3 ). 13 c nmr : 201 . 43 ( c - 5 ), 168 . 72 ( c och 3 ), 89 . 61 ( c - 1 ), 42 . 86 ( c - 4 ), 32 . 10 ( c - 2 ), 20 . 54 ( c h 3 ). 15 . 62 ( c - 3 ). analysis : calc &# 39 ; d for c 9 h 14 o 5 - c , 53 . 46 ; h 6 . 98 . the compound was prepared from 4 - penten - 1 , 1 - diacetate ( 14 ) ( 4 . 65 g , 3 . 45 ml , 25 mmol ) in ch 2 cl 2 ( 5 ml ) as described for ( 10 ). after removing the excess of methyl sulfide by distillation , the residue was subjected to a column chromatography on silica gel ( ch 2 cl 2 ) to give the desired aldehyde ( 15 ) ( 4 . 04 g , 21 . 5 mmol , 86 %) as a colorless oil . 1 h nmr : 9 . 83 ( t , 1 h , j = 1 hz , h - 4 ), 6 . 75 ( t , 1 h , j = 5 hz , h - 1 ), 2 . 66 ( dt , 2 h , j = 5 . 5 , 1 hz , h - 3 ), 2 . 14 ( s , 6 h , ch 3 ), 2 . 05 ( m , 2 h , h - 2 ). 13 c nmr : 201 . 43 ( c - 4 ), 168 . 72 ( c och 3 ), 89 . 61 ( c - 1 ), 42 . 86 ( c - 3 ), 32 . 10 ( c - 2 ), 20 . 54 ( c h 3 ). the compound was prepared from 6 - hepten - 1 , 1 - diacetate ( 19 ) ( 5 . 35 g , 3 . 5 ml , 25 mmol ) in ch 2 cl 2 ( 5 ml ) as described for ( 10 ). after removing the excess of methyl sulfide by distillation , the residue was subjected to a column chromatography on silica gel ( ch 2 cl 2 ) to give the desired aldehyde ( 20 ) ( 4 . 71 g 21 . 8 mmol , 87 %) as a colorless oil . 1 h nmr : 9 . 83 ( t , 1 h , j = 1 hz , h - 6 ), 6 . 75 ( t , 1 h , j = 5 hz , h - 1 ), 2 . 66 ( dt , 2 h , j = 5 . 5 , 1 hz , h - 5 ), 2 . 14 ( s , 6 h , ch 3 ), 2 . 05 ( m , 2 h , h - 2 ), 1 . 85 ( m , 2 h , h - 3 ), 1 . 82 ( m , 2h , h - 4 ). 13 c nmr : 201 . 43 ( c - 6 ), 168 . 72 ( c och 3 ), 89 . 61 ( c - 1 ), 42 . 86 ( c - 5 ), 32 . 10 ( c - 2 ), 20 . 54 ( c h 3 ), 15 . 62 ( c - 3 ), 15 . 60 ( c - 4 ). the compound was prepared from 8 - nonen - 1 , 1 - diacetate ( 23 ) ( 6 . 05 g , 25 mmol ) in ch 2 cl 2 ( 5 ml ) as described for ( 10 ). after removing the excess of methyl sulfide by distillation , the residue was subjected to a column chromatography on silica gel ( ch 2 cl 2 ) to give the desired aldehyde ( 24 ) ( 5 . 12 g , 21 mmol , 84 %) as a colorless oil . 1 h nmr : 9 . 83 ( t , 1 h , j = 1 hz , h - 8 ), 6 . 75 ( t , 1 h , j = 5 hz , h - 1 ), 2 . 66 ( dt , 2 h , j = 5 . 5 , 1 hz , h - 7 ), 2 . 14 ( s , 6 hi ch 3 ), 2 . 05 ( m , 2 h , h - 2 ), 1 . 85 ( m , 2 h . h - 3 ), 1 . 82 - 1 . 75 ( m , 6h , h - 4 , h - 5 , h - 6 ). 13 c nmr : 201 . 50 ( c - 8 ), 168 . 70 ( c och 3 ), 89 . 66 ( c - 1 ), 42 . 88 ( c - 7 ), 32 . 15 ( c - 2 ), 20 . 58 ( c h 3 ), 15 . 62 (* c - 3 ), 15 . 60 (* c - 4 ), 15 . 46 (* c - 5 ), 15 . 00 (* c - 6 ). assignments for c 3 , c 4 , c 5 and c 6 may be interchanged . the compound was prepared from 3 -( allyloxy ) propane - 1 , 1 - diacetate ( 26 ) ( 5 . 4 g , 25 mmol ) in ch 2 cl 2 ( 5 ml ) as described for ( 10 ). after removing the excess of methyl sulfide by distillation , the residue was subjected to a column chromatography on silica gel ( ch 2 cl 2 ) to give the desired aldehyde ( 27 ) ( 4 . 58 g , 21 mmol , 84 %) as a colorless oil . 1 h nmr : 9 . 63 ( t , 1 h , j = 1 hz , h - 1 ′), 6 . 74 ( t , 1 h , j = 4 . 2 hz , h - 1 ), 4 . 27 ( d , 2 h , j = 1 hz , h - 2 ′), 3 . 45 ( t , 2 h , j = 4 . 2 hz , h - 3 ), 2 . 01 ( s , 6 h , ch 3ar ), 1 . 95 ( dt , 2 h , j = 4 , 2 hz , h - 2 ). 13 c nmr : 199 . 94 ( c - 1 ′), 168 . 35 ( c och 3 ), 88 . 37 ( c - 1 ), 72 . 32 ( c - 2 ′), 64 . 66 ( c - 3 ), 33 . 35 ( c - 2 ), 20 . 36 ( c h 3 ). analysis calc &# 39 ; d for c 9 h 14 o 6 : c , 49 . 54 ; h , 6 . 47 . the compound was prepared from 2 , 2 - dimethyl - 4 - pentene - 1 , 1 - diacetate ( 29 ) ( 5 . 32 g , 3 . 54 ml , 25 mmol ) in ch 2 cl 2 ( 5 ml ) as described for ( 10 ). after removing the excess of methyl sulfide by distillation , the residue was subjected to a column chromatography on silica gel ( ch 2 cl 2 ) to give the desired aldehyde ( 30 ) ( 4 . 68 g , 21 . 8 mmol , 87 %) as a colorless oil . 1 h nmr : 9 . 85 ( t , 1 h , j = 1 hz , h - 4 ), 6 . 65 ( t , 1 h , j = 5 hz , h - 1 ), 2 . 08 ( s , 6 h , ch 3ac ), 2 . 01 ( m , 2 h , h - 3 ), 1 . 85 ( s , 6 h , ch 3 ). 13 c nmr : 201 . 05 ( c - 4 ), 168 . 72 ( c och 3 ), 89 . 65 ( c - 1 ), 42 . 80 ( c - 3 ), 37 . 42 ( c - 2 ), 21 . 50 ( c h 3 ), 20 . 35 ( c h 3ac . ). analysis calc &# 39 ; d . for c 10 h 16 o 5 : c , 55 . 55 ; h , 7 . 46 . this compound was prepared in four steps from anhydrous glycerol by monoalkylation , oxidation of the diol , acetylation and ozonolysis koh ( 11 . 2 g , 200 mmol ) was added cautiously to anhydrous glycerol ( 60 ml , 821 mmol ) in a 250 ml flask , and the mixture was heated to 60 ° c . under a nitrogen atmosphere until the koh had dissolved . after cooling to room temperature , allyl bromide ( 17 . 3 ml , 20 mmol ) was added over 15 min , dropwise with stirring and the mixture was stirred at 90 ° c . for 14 h . after cooling to room temperature , the mixture was diluted with aqueous 50 % k 2 co 3 ( 100 ml ) then extracted with ch 2 cl 2 ( 3 × 100 ml ). the combined extracts were dried , filtered and evaporated . the residual diol , a colorless oil , 22 . 5 g ( 32 ) ( 170 mmol , 85 %), was used for subsequent reaction without further purification . 1 h nmr : 5 . 92 ( m , 1 h , h - 2 ′), 5 . 21 ( m , 2 h , h - 3 ′), 4 . 14 ( m , 1 h , h - 2 ), 3 . 97 ( m , 2 h , h - 3 ), 3 . 79 ( m , 2 h , h - 1 ′), 3 . 71 ( m , 2 h , h - 1 ). 13 c nmr : 134 . 19 ( c - 2 ′), 117 . 18 ( c - 3 ′), 72 . 09 ( c - 1 ′), 71 . 11 ( c - 1 ), 70 . 74 ( c - 2 ), 63 . 72 ( c - 3 ). this diol ( 32 ) ( 1 . 71 ml , 2 . 5 g , 18 . 9 mmol ) was added slowly , with stirring , over 10 min to a solution of naio 4 ( 4 . 1 g ) in water ( 45 ml ) under ice cooling and then left at room temperature for 2 h . ethanol ( 30 ml ) was added and the mixture was filtered to remove precipitated sodium salts , and concentrated . chloroform ( 50 ml ) and h 2 o ( 20 ml ) were added , and the organic layer was separated , dried , filtered , and evaporated to dryness . the residue was chromatographed on silica gel ( 96 : 4 chcl 3 / meoh ) to give allyloxy glycol aldehyde ( 33 ) as a colorless liquid ( 1 . 32 g , 13 . 2 mmol , 70 %). 1 h nm : 9 . 73 ( t , 1 h , j = 1 hz , h - 1 ), 5 . 95 ( m , 1 h , h - 2 ′), 5 . 37 ( m , 2 h , h - 3 ′), 4 . 05 ( m , 4 h , h - 1 , h - 2 ). 13 c nmr : 199 . 86 ( c - 1 ), 133 . 32 ( c - 2 ′), 117 . 02 ( c - 3 ′), 74 . 65 ( c - 2 ), 71 . 64 ( c - 1 ′). the aldehyde ( 33 ) ( 1 . 32 g , 13 . 2 mmol ) was added dropwise , with stirring , over 5 min at ambient temperature to a solution of acetic anhydride ( 1 . 5 ml , 16 . 5 mmol ), et 2 o ( 5 ml ) and bf 3 . et 2 o ( 0 . 1 ml ). the reaction mixture was stirred for 10 min then washed sucessively with 25 % naoac solution ( 5 ml ) and h 2 o ( 10 ml × 2 ), and dried over anhydrous na 2 so 4 . after removing the excess of acetic anhydride by distillation , the residue was subjected to a column chromatography on silica gel ( 97 : 3 chcl 3 / meoh ) to give the diacetoxyacetal ( 34 ) ( 2 . 55 g , 12 . 6 mmol , 95 %). 1h nmr : 6 . 82 ( t , 1 h , j = 5 hz , h - 1 ), 5 . 75 ( m , 1 h , h - 2 ′), 5 . 15 ( m , 2 h , h - 3 ′), 3 . 98 ( m , 2 h , h - 1 ′), 3 . 55 ( d , 2 h , j = 5 hz , h - 2 ), 2 . 09 ( s , 6 h , ch 3 ). 13 c nmr : 168 . 33 ( c och 3 ) 133 . 74 ( c - 2 ′), 117 . 21 ( c - 3 ′), 87 . 34 ( c - 1 ), 72 . 04 ( c - 1 ′), 68 . 53 ( c - 2 ), 20 . 31 ( c h 3 ). the diacetoxy acetal ( 34 ) ( 2 . 55 g , 12 . 6 mmol ) in ch 2 cl 2 ( 5 ml ) was ozonized as described for compound ( 10 ). methyl sulfide ( 3 . 7 ml , 50 . 5 mmol , 4 equiv .) was added to the blue ozonide sulution and the mixture was stirred overnight . evaporation of solvent and unreacted methyl sulfide , and chromatography on silica gel ( ch 2 cl 2 eluent ) gave the corresponding aldehyde ( 35 ), ( 2 . 21 g , 10 . 84 mmol , 86 %). 1 h nmr : 9 . 62 ( t , 1 h , j = 1 hz , h - 1 ′), 6 . 84 ( t , 1 h , j = 5 . 2 hz , h - 1 ), 4 . 23 ( d , 2 h , j = 1 hz , h - 2 ′), 3 . 86 ( d , 2 h , j = 5 . 2 hz , h - 2 ), 2 . 01 ( s , 6 h , ch 3 ). 13 c nmr : 199 . 94 ( c - 1 ′), 168 . 35 ( c och 3 ), 87 . 37 ( c - 1 ), 72 . 32 ( c - 2 ′), 68 . 51 ( c - 2 ), 20 . 35 ( c h 3 ). analysis calc &# 39 ; d . for c 8 h 12 o 6 : c , 47 . 06 ; h , 5 . 92 . a solution of heptenoic acid ( 1 . 1 ml , 1 g , 7 . 8 mmol ) in ethanol ( 2 ml ) was added to a stirred solution of p - toluene sulfonic acid ( 0 . 19 g , 1 mmol ) in ethanol ( 10 ml ). the mixture was stirred at 60 ° c . for 2 h , then allowed to cool to room temperature . aqueous nahco 3 ( 50 %) was added ( 25 ml ), and the organic layer was extracted with ch 2 cl 2 ( 2 × 25 ml ), dried over na 2 so 4 , filtered and evaporated . the colorless oil which remained was identified as the desired ester ( 16 ), ( 1 . 19 g , 7 . 64 mmol , 98 %). 1h nmr : 5 . 83 ( m , 1 h , h - 6 ), 4 . 96 ( m , 2 h , h - 7 ), 4 . 15 ( q , 2 h , q , j = 7 hz , oc h 2 ch 3 ), 2 . 36 ( t , j = 7 . 2 hz , 2 h , h - 2 ), 2 . 05 ( q , j = 8 hz , 2 h , h - 5 ), 1 . 61 ( m , 2 h , h - 3 ), 1 . 45 ( m , 2 h , h - 4 ), 1 . 33 ( t , 3 h , j = 7 hz , och 2 c h 3 ). 13 c nmr : 173 . 34 ( c - 1 ), 138 . 01 ( c - 6 ), 114 . 32 ( c - 7 ), 58 . 83 ( o c h 2 ch 3 ), 33 . 82 ( c - 2 ), 33 . 01 ( c - 5 ), 28 . 02 ( c - 3 ), 24 . 14 ( c - 4 ), 13 . 72 ( och2 c h3 ). a solution of the ester ( 16 ), ( 0 . 6 g , 3 . 85 mmol ) in thf ( 5 ml ) was cooled to 0 ° c . in an ice / salt bath . a solution of dibal ( 1 m in hexane , 6 ml , 6 mmol ) was added dropwise with stirring over 10 min . the solution was then warmed to ambient temperature and allowed to stir for an additional 2 h . the excess dibal was carefully quenched by the addition of 10 ml of h 2 o . the organic layer was extracted with chcl 3 ( 2 × 15 ml ), combined , and dried over na 2 so 4 . evaporation of the solvent , chromatography on silica gel ( 93 : 7 chcl 3 / meoh ) gave the alcohol ( 17 ) as a colorless oil ( 0 . 4 g , 3 . 54 mmol , 92 %). 1 h nmr : 5 . 85 ( m , 1 h , h - 6 ), 4 . 95 ( m , 2 h , h - 7 ), 3 . 62 ( t , 2 h , j = 6 hz , h - 1 ), 2 . 62 ( bs , 1 h , o h ), 2 . 02 ( m , 2 h , h - 2 ), 1 . 54 ( m , 2 h , h - 5 ), 1 . 55 ( m , 4 h , h - 3 , h - 4 . 13 c nmr : 138 . 76 ( c - 6 ), 114 . 24 ( c - 7 ), 62 . 5 ( c - 1 ), 33 . 62 ( c - 2 ), 32 . 47 ( c - 5 ), 28 . 60 (* c - 3 ), 25 . 11 (* c - 4 ). a stirred solution of doxorubicin hydrochloride ( 20 mg , 0 . 035 mmol ) and 5 - pentanal - 1 , 1 - diacetate ( 10 ) ( 14 mg , 2 eq , 0 . 07 mmol ) in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ) was treated with a solution of nabh 3 cn ( 1m in thf ) ( 24 ul , 0 . 67 eq , 0 . 024 mmol ). the mixture was stirred under a nitrogen atmosphere at room temperature in the dark for 1 h . when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 10 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 16 mg ). preparative tlc of this product (, chcl 3 — meoh , 10 : 1 ; f f = 0 . 60 ) afforded n -( pentan - 5 - al diacetoxy acetal ) doxorubicin ( 10 mg , 0 . 0137 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 10 . 25 mg , 0 . 0134 mmol , 38 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1 h nmr ( free base ): 8 . 01 ( dd , j = 8 . 2 , 0 . 9 hz , 1 h , h - 1 ), 7 . 82 ( t , j = 8 . 2 hz , 1 h , h - 2 ), 7 . 39 ( dd , j = 8 . 2 , 0 . 9 hz , 1 h , h - 3 ), 6 . 73 ( t , j = 5 . 46 , 1 h , h - 5 ″), 5 . 52 ( t , j = 1 hz , 1 h , h - 1 ′), 5 . 3 ( bs , 1 h , h - 7 ), 4 . 75 ( s , 2 h , h - 14 ), 4 . 12 ( s , 3 h , ch 3ar . ), 3 . 62 ( bs , 1 h , h - 5 ′), 3 . 62 ( m , 1 h , h - 4 ′), 3 . 25 ( d , j = 16 hz , 1 h , h - 10a ), 2 . 95 ( d , j = 16 hz , 1 h , h - 10b ), 2 . 85 ( m , 1 h , h - 3 ′), 2 . 65 ( m , 2 h , h - 1 ″), 2 . 35 ( m , 1 h , h - 8a ), 2 . 25 ( m , 1 h , h - 8b ), 2 . 01 ( s , 6 h , ch 3ac . ), 1 . 82 ( m , 2 h , h - 2 ′ a ), 1 . 76 ( m , 2 h , h - 4 ″), 1 . 75 ( m , 1 h , h - 2 ′ b ), 1 . 40 ( m , 2 h , h - 3 ″), 1 . 35 ( d , j = 6 hz , 3 h , h - 6 ′). the compound was prepared from doxorubicin hcl ( 20 mg , 0 . 035 mmol , o -( 2 , 2 - diacetoxyethyl ) glycolaldehyde ( 35 ) ( 14 . 3 mg , 2 eq ., 0 . 07 mmol ), nabh 3 cn ( 1 m in thf ) ( 24 ul , 0 . 67 eq , 0 . 024 mmol ) in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ), as desribed for ( 2a ). when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 10 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 17 . 5 mg ). preparative tlc of this product ( chcl 3 — meoh , 10 : 1 ; r f = 0 . 6 ) afforded n -( 2 , 2 - diacetoxyethyloxyethyl ) doxorubicin ( 9 . 1 mg , 0 . 012 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 9 . 4 mg , 0 . 012 mmol , 34 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1 h nmr ( free base ): 8 . 11 ( dd , j = 8 . 2 , 0 . 8 hz , 1 h , h - 1 ), 7 . 82 ( t , j = 8 . 2 hz , 1 h , h - 2 ), 7 . 35 ( dd , j = 8 . 2 , 0 . 8 hz , 1 h , h - 3 ), 6 . 75 ( t , 1 h , j = 5 . 5 , h - 1b ″) 5 . 50 ( t , j = 1 hz , 1 h , h - 1 ′), 5 . 35 ( bs , 1 h , h - 7 ), 4 . 75 ( s , 2 h , h - 14 ), 4 . 11 ( s , 3 h , ch 3ar . ), 3 . 84 ( bs , 1 h , h - 5 ′), 3 . 77 ( m , 1 h , h - 4 ′), 3 . 65 ( m , 2 h , h - 2 ″ a ), 3 . 54 ( m , 2 h , h - 2b ″), 3 . 25 ( d , j = 16 hz , 1 h , h - 10a ), 3 . 21 ( m , 1 h , h - 3 ′), 3 . 14 ( m , 2 h , h - 1 ″), 2 . 95 ( d , j = 16 hz , 1 h , h - 10b ), 2 . 35 ( m , 1 h , h - 8a ), 2 . 25 ( m , 1 h , h - 8b ), 2 . 24 ( m , 2 h , h - 2 ′ a ), 2 . 12 ( m , 1 h , h - 2 ′ b ), 2 . 01 ( s , 6 h , ch 3ac . ), 1 . 34 ( d , j = 6 hz , 3 h , h - 6 ′). the compound was prepared from doxorubicin . hcl ( 20 mg , 0 . 035 mmol ), 4 - butanal - 1 , 1 - diacetate ( 15 ) ( 13 . 2 mg , 2 eq ., 0 . 07 mmol ) and nabh 3 cn ( 1 m in thf ) ( 24 ul , 0 . 67 eq ., 0 . 024 mmol ) in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ) as described for ( 2a ). when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 9 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 15 mg ). preparative tlc of this product ( chcl 3 — meoh , 10 : 1 ; r f = 0 . 59 ) afforded ( 4 , 4 - diacetoxybutyl ) doxorubicin ( 10 mg , 0 . 014 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 10 . 17 mg , 0 . 0135 mmol , 39 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1 h nmr ( free base ): 8 . 05 ( dd , j = 8 . 1 , 0 . 85 hz , 1 h , h - 1 ), 7 . 90 ( t , j = 8 . 1 hz , 1 h , h - 2 ), 7 . 42 ( dd , j = 8 . 1 , 0 . 85 hz , 1 h , h - 3 ), 6 . 75 ( t , j = 5 . 45 hz , 1 h , h - 4 ″), 5 . 52 ( bs , 1 h , h - 1 ′), 5 . 31 ( bs , 1 h , h - 7 ), 4 . 72 ( s , 2 h , h - 14 ), 4 . 05 ( s , 3 h , ch 3ar . ), 3 . 65 ( bs , 1 h , h - 5 ′), 3 . 61 ( m , 1 h , h - 4 ′), 3 . 32 ( d , j = 16 . 2 hz , 1 h , h - 10a ), 3 . 03 ( d , j = 16 . 2 hz , 1 h , h - 10b ), 2 . 81 ( m , 1 h , h - 3 ′), 2 . 60 ( m , 2 h , h - 1 ″), 2 . 44 ( m , 1 h , h - 8a ), 2 . 22 ( m , 1 h , h - 8b ), 2 . 02 ( s , 6 h , ch 3ac . ), 1 . 75 ( m , 2 h , h - 2 ′ a ), 1 . 75 ( m , 2 h , h - 3 ″), 1 . 71 ( m , 1 h , h - 2 ′ b ), 1 . 42 ( m , 2 h , h - 2 ″), 1 . 35 ( d , j = 6 hz , 3 h , h - 6 ′). a stirred solution of doxorubicin hydrochloride ( 20 mg , 0 . 035 mmol ) and 6 - hexanal - 1 , 1 - diacetate ( 20 ) ( 15 mg , 2 eg , 0 . 07 mmol ) in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ) was treated with a solution of nabh 3 cn ( 1m in thf ) ( 24 ul , 0 . 67 eq , 0 . 024 mmol ). the mixture was stirred under a nitrogen atomosphere at room temperature in the dark for 1 hour . when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 10 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 18 mg ). preparative tlc of this product ( chcl 3 — meoh , 10 : 1 ; f f = 0 . 60 ) afforded n -( 6 , 6 - diacetoxyhexyl ) doxorubicin ( 10 . 4 mg , 0 . 014 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 10 . 75 mg , 0 . 0138 mmol , 39 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1 h nmr ( free base ): 8 . 03 ( dd , j = 8 . 2 , 0 . 9 hz , 1 h , h - 1 ), 7 . 84 ( t , j = 8 . 2 hz , 1 h , h - 2 ), 7 . 37 ( dd , j = 8 . 2 , 0 . 9 hz , 1 h , h - 3 ), 6 . 76 ( t , j = 5 . 46 , 1 h , h - 6 ″), 5 . 52 ( t , j = 1 hz , 1 h , h - 1 ′), 5 . 4 ( bs , 1 h , h - 7 ), 4 . 75 ( s , 2 h , h - 14 ), 4 . 14 ( s , 3 h , ch 3ar . ), 3 . 65 ( bs , 1 h , h - 5 ′), 3 . 63 ( m , 1 h , h - 4 ′), 3 . 25 ( d , j = 16 hz , 1 h , h - 10a ), 2 . 96 ( d , j = 16 hz , 1 h , h - 10b ), 2 . 85 ( m , 1 h , h - 3 ′), 2 . 66 ( m , 2 h , h - 1 ″), 2 . 36 ( m , 1 h , h - 8a ), 2 . 23 ( m , 1 h , h - 8b ), 2 . 05 ( s , 6 h , ch 3ac . ), 1 . 82 ( m , 2 h , h - 2 ′ a ), 1 . 78 ( m , 2 h , h - 5 ″), 1 . 75 ( m , 1 h , h - 2 ′ b ), 1 . 65 ( m , 2 h , h - 2 ″), 1 . 40 ( m , 2 h , h - 3 ″), 1 . 39 ( m , 2 h , h - 4 ″), 1 . 32 ( d , j = 6 hz , 3 h , h - 6 ′). the compound was prepared from doxorubicin hcl ( 20 mg , 0 . 035 mmol ), dimethyl 2 , 2 - dimethyl - 4 - butanal - 1 , 1 - diacetate ( 30 ) ( 15 mg , 2 eq ., 0 . 07 mmol ) and nabh 3 cn ( 1 m in thf ) ( 24 ul , 0 . 67 eq ., 0 . 024 mmol ), in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ), as described for ( 2a ). when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 9 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 17 mg ). preparative tlc of this product ( chcl 3 — meoh , 10 : 1 ; r f = 0 . 54 ) afforded n -( 4 , 4 - diacetoxy - 3 , 3 — dimethylbutyl ) doxorubicin ( 11 . 2 mg , 0 . 015 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 10 . 8 mg , 0 . 0138 mmol , 39 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1 h nmr ( free base ): 8 . 02 ( dd , j = 8 . 15 , 0 . 83 hz , 1 h , h - 1 ), 7 . 91 ( t , j = 8 . 15 hz , 1 h , h - 2 ), 7 . 54 ( dd , j = 8 . 15 , 0 . 83 hz , 1 h , h - 3 ), 6 . 65 ( s , 1 h , h - 4 ″), 5 . 52 ( bs , 1 h , h - 1 ′), 5 . 35 ( bs , 1 h , h - 7 ), 4 . 72 ( s , 2 h , h - 14 ), 4 . 03 ( s , 3 h , ch 3ar . ), 3 . 65 ( bs , 1 h , h - 5 ′), 3 . 60 ( m , 1 h , h - 4 ′), 3 . 35 ( d , j = 16 . 4 hz , 1 h , h - 10a ), 3 . 05 ( d , j = 16 . 4 hz , 1 h , h - 10b ), 2 . 95 ( m , 1 h , h - 3 ′), 2 . 61 ( m , 2 h , h - 1 ″), 2 . 40 ( m , 1 h , h - 8a ), 2 . 26 ( m , 1 h , h - 8b ), 2 . 01 ( s , 6 h , ch 3ac . ), 1 . 78 ( m , 2 h , h - 2 ′ a ), 1 . 73 ( m , 1 h , h - 2 ′ b ), 1 . 55 ( s , 6 h , ch 3 ), 1 . 52 ( m , 2 h , h - 2 ″), 1 . 35 ( d , j = 6 hz , 3 h , h - 6 ′). the compound was prepared from doxorubicin hcl ( 20 mg , 0 . 035 mmol , 3 , 3 - diacetatepropyloxy - 1 - ethanal ( 27 ) ( 15 . 2 mg , 2 eq ., 0 . 07 mmol ), nabh 3 cn ( 1 m in thf ) ( 24 ul , 0 . 67 eq , 0 . 024 mmol ) in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ), as desribed for ( 2a ). when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 10 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 17 . 5 mg ). preparative tlc of this product ( chcl 3 — meoh , 10 : 1 ; r f = 0 . 6 ) afforded n -( 3 , 3 - diacetoxypropyloxyethyl ) doxorubicin ( 9 . 1 mg , 0 . 012 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 9 . 4 mg , 0 . 012 mmol , 34 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1h nmr ( free base ): 8 . 10 ( dd , j = 8 . 1 , 0 . 8 hz , 1 h , h - 1 ), 7 . 82 ( t , j = 8 . 1 hz , 1 h , h - 2 ), 7 . 34 ( dd , j = 8 . 1 , 0 . 8 hz , 1 h , h - 3 ), 6 . 73 ( t , j = 5 . 4 hz , 1 h , h - 1 ″ c ) 5 . 52 ( t , j = 1 hz , 1 h , h - 1 ′), 5 . 4 ( bs , 1 h , h - 7 ), 4 . 73 ( s , 2 h , h - 14 ), 4 . 12 ( s , 3 h , ch 3ar . ), 3 . 82 ( bs , 1 h , h - 5 ′), 3 . 75 ( m , 1 h , h - 4 ′), 3 . 62 ( m , 2 h , h - 2 ″ a ), 3 . 53 ( m , 2 h , h - 2b ″), 3 . 25 ( d , j = 16 hz , 1 h , h - 10a ), 3 . 20 ( m , 1 h , h - 3 ′), 3 . 15 ( m , 2 h , h - 1 ″ a ), 2 . 95 ( d , j = 16 hz , 1 h , h - 10b ), 2 . 38 ( m , 1 h , h - 8a ), 2 . 35 ( m , 1 h , h - 8b ), 2 . 24 ( m , 2 h , h - 2 ′ a ), 2 . 15 ( m , 1 h , h - 2 ′ b ), 2 . 02 ( s , 6 h . ch 3ac . ), 1 ), 1 . 95 ( dt , 2 h , j = 5 . 4 , 2 hz , h - 2 ″ b ), 1 . 35 ( d , j = 6 hz , 3 h , h - 6 ′). a stirred solution of doxorubicin hydrochloride ( 20 mg , 0 . 035 mmol ) and 8 - octanal - 1 , 1 - diacetate ( 24 ) ( 17 . 1 mg , 2 eg , 0 . 07 mmol ) in ch 3 cn — h 2 o ( 2 : 1 ) ( 5 ml ) was treated with a solution of nabh 3 cn ( 1m in thf ) ( 24 ul , 0 . 67 eg , 0 . 024 mmol ). the mixture was stirred under a nitrogen atmosphere at room termperature in the dark for 1 hour . when reaction was complete ( as evidenced by tlc of a 5 ul aliquot ) the solution was diluted with h 2 o ( 8 ml ) and then extracted repeatedly ( 10 × 10 ml ) with chcl 3 — meoh ( 5 : 1 ). the combined extracts were dried and evaporated to give a red amorphous solid ( 19 mg ). preparative tlc of this product ( chcl 3 — meoh , 10 : 1 ; r f = 0 . 60 ) afforded n -( 8 , 8 - diacetoxyoctyl ) doxorubicin ( 11 . 6 mg , 0 . 015 mmol ). the product was suspended in h 2 o ( 1 ml ) and acidified to ph 5 by dropwise addition of 0 . 05 n hcl ( approx . 0 . 5 ml ). the solution was lyophilized to afford the title compound ( 11 . 72 mg , 0 . 0145 mmol , 41 %). it was then stored under a nitrogen atmosphere in a tightly stoppered vessel at − 78 ° c . in the dark . 1 h nmr ( free base ): 8 . 05 ( dd , j = 8 . 2 , 0 . 9 hz , 1 h , h - 1 ), 7 . 85 ( t , j = 8 . 2 hz , 1 h , h - 2 ), 7 . 40 ( dd , j = 8 . 2 , 0 . 9 hz , 1 h , h - 3 ), 6 . 72 ( t , j = 5 . 46 , 1 h , h - 8 ″), 5 . 55 ( t , j = 1 hz , 1 h , h - 1 ′), 5 . 35 ( bs , 1 h , h - 7 ), 4 . 71 ( s , 2 h , h - 14 ), 4 . 16 ( s , 3 h , ch 3ar . ), 3 . 68 ( bs , 1 h , h - 5 ′), 3 . 65 ( m , 1 h , h - 4 ′), 3 . 28 ( d , j = 16 hz , 1 h , h - 10a ), 2 . 98 ( d , j = 16 hz , 1 h , h - 10b ), 2 . 85 ( m , 1 h , h - 3 ′), 2 . 68 ( m , 2 h , h - 1 ″), 2 . 35 ( m , 1 h , h - 8a ), 2 . 25 ( m , 1 h , h - 8b ), 2 . 04 ( s , 6 h , ch 3ac . ), 1 . 85 ( m , 2 h , h - 2 ′ a ), 1 . 75 ( m , 2 h , h - 7 ″), 1 . 76 ( m , 1 h , h - 2 ′ b ), 1 . 68 ( m , 2 h , h - 2 ″), 1 . 41 ( m , 2 h , h - 3 ″), 1 . 40 ( m , 6 h , h - 4 ″, h - 5 ″), 1 . 39 ( m , 2 h , h - 6 ″), 1 . 35 ( d , j = 6 hz , 3 h , h - 6 ′). by usage of analogous cogeners , those of skill in the art may readily adopt the above synthetic methods to produce almost innumerable varieties of the subject compounds . the following references as well as those listed in the body of the specification are incorporated in pertinent part herein for the reasons cited . 1 . young , r . c . ; ozols , r . f . ; myers , c . e . n . engl . j . med . 1981 , 305 , 139 . 3 . brown , j . r . ; imam , s . h . progr . med . chem . 1984 , 21 , 169 . 4 . muggia f . m . ; young c . w . ; carter s . k . 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