5-halo-5-deoxy sorbopyranose compounds

Abstract: The present invention relates to a method of preparing BCH-189 and various analogues of BCH-189 from inexpensive precursors with the option of introducing functionality as needed. This synthetic route allows the stereoselective preparation of the biologically active isomer of these compounds, β-BCH-189 and related compounds. Furthermore, the stereochemistry at the nucleoside 4'-position can be controlled to produce enantiomerically-enriched β-BCH-189 and its analogues.

Description: Sulfamates of various structures, including those derived from monosaccharides, are described in J. Med . Chem . 1987, 30 , 88 and in U.S. Patent No. 4,075,351. Certain of these sulfamates are useful as pharmaceutical agents. More recently, sulfamates having various pharmaceutical activity in the areas of epilepsy, glaucoma, peptic ulcers, and male infertility are described in U.S. Patents Nos. 4,513,006, 4,459,601 and 4,792,569. One of the compounds covered by U.S. Patent 4,513,006, topiramate, has not only been found to exhibit particularly significant anticonvulsant activity in animals, but also appears to be useful in humans for the treatment of epilepsy ( Drugs Future 1989, 14 , 342). While sulfamate compounds of the type disclosed in U.S. Patent No. 4,513,006 have been shown to exhibit useful biological activity when administered to mammals, other compounds with equal or improved activity compared to topiramate would be desirable. Presently, there are no previously reported sulfamate derivatives that contain the L-sorbopyranose structure. In addition, there are only two literature reports of L-sorbopyranose derivatives containing a 2,3-ketal or 2,3-acetal moiety (Chan; J. Y.C.; Cheong, P.O.L; Hough, L; Richardson, A.C. J . Chem . Soc . Perkin Trans. I , 1985, 1447 and Martin, O.R.; Korppi-Tommola, S.L.; Szarek, W.A. Can. J . Chem. 1982, 60, 1857). EP-A-0675893, of which the present application is a divisional, describes certain sulfamate derivatives represented by the formula (I): Wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are as defined hereinafter. These sulfamates exhibit anticonvulsant activity. As a result, the compounds and pharmaceutical compositions containing such compounds are useful for the treatment of convulsions such as epileptic seizures. Compounds useful as intermediates to prepare compounds of the formula (I) are provided by the present invention. More particularly, the compounds of EP-A-0675893 are represented by the following formula (I): wherein R 1 and R 2 are the same or different and are selected from any of hydrogen or C 1 to C 4 alkyl. Preferably, R 1 and R 2 are each hydrogen. R 3 and R 4 are the same or different and are selected from any of hydrogen or C 1 to C 4 alkyl. Preferably, R 3 and R 4 are each C 1 to C 4 alkyl. R 5 and R 6 are the same or different and are selected from any of azido, halogen, hydroxyl, sulfamoyl (H 2 NSO 2 O), C 1 to C 4 alkoxy, C 1 to C 4 alkyl thiocarbonate (RSC(O)O), C 1 to C 4 alkyl carbonate (ROC(O)O), or C 1 to C 4 alkyl carboxylate (RC(O)O), wherein R is C 1 to C 4 alkyl, provided that R 5 and R 6 are not both hydroxyl. Preferably, R 5 and R 6 are selected from any of C 1 -C 4 alkyl thiocarbonate, halogen or hydroxyl. As used herein, the terms alkyl and alkoxy include straight and branched chains. For example, alkyl radicals include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, and t-butyl. Halogen includes bromine, chlorine, fluoride and iodine. Preferred compounds of the formula (I) are those wherein the pyran ring is in the L-sorbopyranose absolute configuration. Particularly preferred compounds of the formula (I) according to EP-A-0675893 are those wherein the pyran ring is in the L-sorbopyranose absolute configuration, R 1 and R 2 are each hydrogen, R 3 and R 4 are each methyl; R 5 is methyl thiocarbonate (CH 3 SC(O)O) and R 6 is halogen; or R 5 and R 6 are both halogen; or R 5 is hydroxyl and R 6 is halogen. Particularly preferred halogens include bromine, chlorine, and iodine. Examples of specific compounds of the formula (I) are: 5-deoxy-5-iodo-2,3- O -(1-methylethylidene)-4-[methylthiocarbonyl)]-α-L-sorbopyranose sulfamate, i.e. where the compound is in the L-sorbopyranose absolute configuration, R 1 and R 2 are hydrogen, R 3 and R 4 are methyl, R 5 is CH 3 SC(O)O, and R 6 is iodine; 4,5-dibromo-4,5-dideoxy-2,3- O -(1-methylethylidene)-α-L-sorbopyranose sulfamate, i.e. where the compound is in the L-sorbopyranose absolute configuration, R 1 and R 2 are hydrogen, R 3 and R 4 are methyl, R 5 and R 6 are bromine; and 5-chloro-5-deoxy-2,3- O -(1-methylethylidene)-α-L-sorbopyranose sulfamate, i.e. where the compound is in the L-sorbopyranose absolute configuration, R 1 and R 2 are hydrogen, R 3 and R 4 are methyl, R 5 is hydroxyl, and R 6 is chlorine. Included within the definition of formula (I) are the various individual anomers, diastereomers and enantiomers as well as mixtures thereof. In addition, the definition of formula (I) includes pharmaceutically acceptable salts, for example; alkali metal salts, such as sodium or potassium, ammonium salts, dialkylammonium salts, trialkylammonium salts, tetraalkylammonium salts, and tromethamine salts. Hydrates and other solvates of the compound of the formula (I) are also included within the definition of formula (I). The compounds of the formula (I) may be synthesized from compounds of the formulas (II-VI), wherein R 1 , R 2 , R 3 , and R 4 are defined as previously described and X is equal to halogen, by one of the following methods. The various isomers, as shown, may be prepared by using the appropriate isomeric starting materials. Specifically, the present invention provides the intermediate compounds of formula (V) as defined in the accompanying claims. The present invention also provides the use of such compounds for the preparation of compounds of formula (I), as defined in the accompanying claims. Alkyl carboxylates of the formula (I), where R 5 is RC(O)O and R 6 is halogen, may be prepared by reaction of a diol of the formula (II) with an acid halide, such as acetyl bromide, in refluxing acetonitrile according to the procedure of Mansuri et al . described in J. Org. Chem . 1989, 54, 4780. For example: Halothiocarbonates of the formula (I), where R 5 is RSC(O)O and R 6 is halogen, may be prepared by reaction of a diol of the formula (II) with 1,1'-thiocarbonyldiimidazole in the presence of a suitable aprotic solvent, such as tetrahydrofuran, dichloromethane, or ethyl acetate, to furnish the corresponding thiocarbonates of the formula (III), which is subsequently reacted with an alkyl halide, such as methyl iodide, in the presence of a suitable ethereal solvent, such as 1,2-dimethoxyethane or tetrahydrofuran, at temperatures above 60°C in a sealed vessel, to provide the halothiocarbonate of the formula (I). For example: Dihalo compounds of the formula (I), where R 5 and R 6 are both halogen, may be prepared by the low temperature addition of halogen halides, such as bromine, iodine, iodine monobromide, and iodine monochloride, to alkenes of the formula (IV) in dichloromethane, chloroform, or toluene at temperatures of from about -78 °C to 0 °C. The requisite alkenes of the formula (IV) may be prepared via reduction of halothiocarbonates of the formula (I) with trialkyl phosphites according to the procedure of Corey and Winter described in J. Am . Chem . Soc . 1963, 85, 2677 or preferably by reduction with Mg(Hg) or zinc as described by Vedejs and Wu in J. Org. Chem. 1974, 39 , 3641. For example: Halohydrin compounds of the formula (I), where R 5 is hydroxyl and R 6 is halogen, may be prepared by the reaction of sulfamoyl chloride (ClSO 2 NH 2 ) with a halohydrin compound of the formula (V) in a polar aprotic solvent, such as tetrahydrofuran or N,N -dimethylformamide, at temperatures of from about -60 °C to 30 °C. For example: Similarly, compounds of the formula (I) where R 5 is sulfamoyl or C 1 to C 4 alkyl carbonate and R 6 is halogen may be prepared by the reaction of halohydrins of the formula (I) with sulfamoyl chloride or alkyl chloroformate, respectively, in a solvent such as tetrahydrofuran or N,N -dimethylformamide, at temperatures of from about -60 °C to 30 °C. For example: Compounds of the formula (I) where R 5 is hydroxyl and R 6 is either halogen, C 1 to C 4 alkoxy, or C 1 to C 4 alkyl carboxylates may be prepared by the reaction of a cyclic sulfate of the formula (VI) with halide salts, C 1 to C 4 alkoxide salts, or C 1 to C 4 carboxylic acid salts, respectively, followed by acid hydrolysis according to the procedures described by Sharpless et al. in J. Am . Chem . Soc . 1988, 110 , 7538 and Tetrahedron Lett . 1989 30 , 655. For example: The starting materials required to synthesize compounds of formula (I) may be prepared by methods known to those skilled in the art of organic synthesis. For example, diols of the formula (II) can be prepared by the procedure described by Maryanoff et al . in J . Med . Chem . 1987, 30, 880. Halohydrin compounds of the formula (V) may be prepared by the method of Martin et al . in Can. J. Chem. 1982, 60 , 1857. Cyclic sulfates of the formula (VI) may be prepared, for example, by reacting a diol of the formula (II) with sulfuryl chloride in the presence of pyridine or triethylamine at a temperature of about -78° to about 25 °C in an aprotic solvent such as ethyl acetate, toluene, or dichloromethane to produce the bis -chlorosulfate of formula (VII). Dechlorosulfation of the bis -chlorosulfate of formula (VII) with a weak base, such as NaHCO 3 or pyridine, in an alcohol such as methanol or ethanol at temperatures from -40° to 25 °C yields cyclic sulfate compounds of the formula (VI). For example: Pharmaceutically acceptable salts of the compounds of formula (I) may be prepared by reacting the sulfamate of formula (I) with the appropriate base and recovering the salt. For example: Compounds of the formulas (III), (IV), and (V), with the proviso that R 3 and R 4 can not both be methyl at the same time for compounds of formula (V), are useful as intermediates to prepare compounds of the formula (I). The compounds of formula (I) are particularly useful as anticonvulsant agents in mammals including humans. The anticonvulsant activity of the subject compounds was determined using a standard "maximal electroshock test" (MES). In this test, activity is indicated by a block of the toxic extensor seizure caused by application of an electric shock to mice via corneal electrodes, as described by Swinyard et al. in J. Pharmacol . Expt. Ther. 1952 , 106 , 319, and recorded as % block. Details of this test are disclosed in the parent of the present application, EP-B-0675893, on page 6, lines 29-45. A more recent description of current anticonvulsant drug screening is given by Swinyard in Epilepsia 1978, 19, 409. For testing compounds, the abolition of the tonic extensor component was the endpoint. Animals were dosed orally (PO) with either vehicle or test drug and at a specified time were given a maximal electric shock through corneal electrodes blotted with saline (as described above). A minimum of 10 animals were used per group and the percentage of animals in the group without tonic hindlimb extension recorded. The anticonvulsant activity of the compounds of this invention tested according to the Swinyard (1952) method is shown in the following Table I. For treating epilepsy, a compound of formula (I) may be employed at a daily dosage in the range of about 10 to 2000 mg, usually in 1 to 4 daily divided doses, for an average adult human. A unit dose would contain about 5 to 500 mg of the active ingredient. This translates to a dose of about 0.1 to 30 mg/kg/day. In general, compounds of formula (I) may be used in treating epilepsy in a manner similar to that used for phenytoin; e.g., orally administering a solid formulation twice/day. Medical aspects of the treatment of epilepsy are described in greater detail by L S. Goodman et al. in "The Pharmacological Basis of Therapeutics", 5th Ed. pages 201 to 226, Macmillan (1975). The details of administering and formulating pharmaceutical compositions of formula (1) are disclosed is the parent of the present application, EP-B-0675893, an page 7, line 30 to page 8, line 6. The following Examples 1 and 2 are comparative examples describing the synthesis of specific compounds of Formula (I). Example 3 describes the use of an intermediate compound of formula (V) in the synthesis of a compound of Formula (I), according to the present invention. EXAMPLE 1: 5-Deoxy-5-iodo-2,3- O -(1-methylethylidene)-4-[methylthio Carbonyl)]-α-L-sorbopyranose Sulfamate 2,3- O -(1-Methylethylidene)-β-D-fructopyranose 1-sulfamate (32.5 g, 0.109 mol; J. Med . Chem. 1987, 30, 880) was combined with 1,1'-thiocarbonyldiimidazole (47.3 g, 0.239 mol), dissolved in 500 mL of THF, and stirred at RT for 6 hr. The solvent was removed in vacuo at 40°C and the residue was dissolved in EtOAc. The EtOAc solution was extracted sequentially twice with 1 N HCl, three times with saturated aqueous NaHCO 3 , once with saturated aqueous NaCl, dried over anhydrous MgSO 4 , filtered through Celite®, and concentrated in vacuo at 40°C to furnish 36.7 g of crude product as brown oil. This material was purified by chromatography on silica gel eluting with CH 2 Cl 2 /EtOAc (4:1 v/v) to provide 15.0 g (40%) of 2,3- O -(1-methylethylidene)-4,5- O -thiocarbonyl-β-D-fructopyranose sulfamate as a white solid. An analytical sample was recrystallized from anhydrous ethanol, m.p. 205-206 °C; [α] D 20 =-75.1° (c = 1.75, CH 3 OH). Anal. Calcd. for C 10 H 15 NO 8 S 2 : C, 35.19; H, 4.43; N, 4.10, S, 18.78. Found: C, 35.40; H, 4.46; N, 4.06, S, 18.84. 2,3- O -(1-Methylethylidene)-4,5- O -thiocarbonyl-β-D-fructopyranose sulfamate (11.11 g, 0.033 mol), methyl iodide (40 6 mL, 0.652 mol) and 1,2-dimethoxyethane (100 mL) were combined in a pressure bottle and heated at 90 °C while stirring for 10 hr. The solvent was removed in vacuo and the residue was purified via chromatography on silica gel eluting with CH 2 Cl 2 /EtOAc (6:1 v/v) to give a white solid (10.43 g, 65%) which was recrystallized from CH 2 Cl 2 /EtOAc to provide the title compound as a white crystalline solid; m.p. 135-136 °C; [α] D 25 = +39.4° (c = 1.00, CH 3 OH). Anal. Calcd. for C 11 H 18 INO 8 S 2 : C, 27.34; H, 3.75; N, 2.90, S, 13.27. Found: C, 27.49; H, 3.52; N, 2.84, S, 13.90. EXAMPLE 2: 4,5-Dibromo-4,5-dideoxy-2,3- O -(1-methylethylidene)-α-L-sorbopyranose Sulfamate. 5-Deoxy-5-iodo-2,3- O -(1-methylethylidene)-4-[methylthiocarbonyl)]-α-L-sorbopyranose sulfamate (Example 1; 14.09 g, 0.029 mol), zinc dust (11.45 g, 0.175 mol), H 2 O (14 mL) and 95% ethanol (140 mL) were combined and heated at reflux while vigorously stirring for 2 hr. After cooling to RT, the reaction was filtered through Celite® and concentrated in vacuo to give 15.5 g of a brown oil, which was purified via chromatography on silica gel eluting with CH 2 Cl 2 /EtOAC (9:1 v/v) to provide 5.42 g of product. This material was dissolved in CHCl 3 and extracted twice with saturated aqueous NaCl, dried over anhydrous MgSO 4 , filtered through Celite® and concentrated in vacuo to give 5.43 g of 4,5-dideoxy-2,3- O -(1-methylethylidene)-β-D-fruct-4-enopyranose sulfamate solvate with chloroform (8:1) as a golden oil; [α] D 25 = -0.9° (c = 1.13, CH 3 OH). Anal. Calcd. for C 9 H 15 NO 6 S•1/8 CHCl 3 : C, 39.11; H, 5.44; N, 5.00. Found: C, 39.25; H, 5.31; N, 4.86. A solution of 4,5-dideoxy-2,3- O -(1-methylethylidene)-β-D-fruct-4-enopyranose sulfamate (1.04 g, 0.0039 mol) in 12 mL of dry CH 2 Cl 2 was cooled to -75 °C while stirring under an argon atmosphere. Bromine (0.51 mL, 0.0098 mol) was added dropwise over 10 min and the reaction was stirred at -75 °C for 1 hr, quenched by the addition of cyclohexene (1 mL, 0.0098 mol), basified with pyridine (0.8 mL, 0.0098 mol), warmed to RT, and purified by chromatography on silica gel eluting with CH 2 Cl 2 /EtOAc (19:1 v/v) to give 1.10 g (66%) of the title compound as a clear glass; [α]D 25 = +20.1° (c = 1.00, CH 3 OH). Anal. Calcd. for C 9 H 15 Br 2 NO 6 S: C, 25.43; H, 3.56; Br, 37.59; N, 3.29; S, 7.54. Found: C, 25.71; H, 3.61; Br, 37.49; N, 3.24; S, 7.61. EXAMPLE 3: 5-Chloro-5-deoxy-2,3- O -(1-methylethylidene)-α-L-sorbopyranose Sulfamate. A solution of 5-chloro-5-deoxy-2,3- O -(1-methylethylidene)-α-L-sorbopyranose (3.00 g, 0.013 mol; Can. J . Chem . 1982, 60, 1857) in dry DMF (25 mL) was cooled to 5 °C while stirring under an argon atmosphere. Sulfamoyl chloride (2.33 g, 0.020 mol) was added and the reaction was stirred at 5 °C for 2.5 hr, diluted with 100 mL of saturated aqueous NaCI, and extracted with three portions of EtOAc. The combined EtOAc extracts were extracted twice with saturated aqueous NaHCO 3 , dried over anhydrous MgSO 4 , filtered through Celite®, and concentrated in vacuo at 40 °C. The residue was purified by chromatography on silica gel eluting with CH 2 Cl 2 /EtOAc (4:1 v/v) and subsequently recrystallized from CH 2 Cl 2 /hexane (2:3) to yield 1.38 g (35%) of the title compound as a white crystalline solid that also contained 0.14 equivalents of 5-chloro-5-deoxy-2,3- O -(1-methylethylidene)-4-sulfamoyl-α-L-sorbopyranose sulfamate (as determined by MS, 1 H NMR, and elemental analysis); mp 94-100 °C; [α]D 25 = +7.7° (c = 1.00, CH 3 OH). Anal. Calcd. for C 9 H 16 ClNO 7 S·0.14 C 9 H 17 ClN 2 O 9 S 2 : C, 33.01; H, 4.96; N, 4.80; S, 10.99. Found: C, 33.15; H, 5.01; N, 4.88; S, 10.94.

Claims: Use of a compound of the formula (V): wherein R 3 and R 4 are the same or different and are selected from hydrogen or C 1 to C 4 alkyl; wherein X is selected from any of bromine, chlorine, fluorine, or iodine; and the individual anomers, diastereomers and enantiomers and mixtures thereof, for the preparation of a compound of formula (I): wherein R 1 and R 2 are the same or different and selected from any of hydrogen or C 1 to C 4 alkyl; wherein R 3 and R 4 are the same or different and are selected from any of hydrogen or C 1 to C 4 alkyl; wherein R 5 and R 6 are the same or different and are selected from any of azido, halogen, hydroxyl, sulfamoyl (H 2 NSO 2 O), C 1 to C 4 alkoxy, C 1 to C 4 alkyl thiocarbonate (RSC(O)O), C 1 to C 4 alkyl carbonate (ROC(O)O), or C 1 to C 4 alkyl carboxylate (RC(O)O), wherein R is C 1 - C 4 alkyl; the individual anomers, diastereomers, enantiomers and mixtures thereof, and the pharmaceutically acceptable salts and solvates thereof. Use according to claim 1, whererin a compound of the formula (V) is reacted with sulfamoyl chloride (CISO 2 NH 2 ) in a polar aprotic solvent at temperatures of from -60°C to +30°C. Use according to claim 1 or 2 in which the compound of formula (V) is 5-chloro-5-deoxy-2,3-O-(1-methylethylidene)-α-L-sorbopyranose.

Inventors: COSTANZO MICHAEL J, MARYANOFF BRUCE E, COSTANZO, MICHAEL J., MARYANOFF, BRUCE E.
Applicants: MCNEILAB INC, MCNEILAB, INC.
Application year: 1993
Main classification: C07H9
IPC codes: C07H9, C07H11