HALOGEN SUBSTITUTED CARBAMATE COMPOUNDS FROM 2-PHENYL-1,2-ETHANEDIOL

Abstract: The optically pure forms of monocarbamates of halogenated 2-phenyl-1,2-ethanediol and dicarbamates of halogenated 2-phenyl-1,2-ethanediol have been found to be effective in treatment of disorders of the central nervous system, especially as anti- convulsive or anti-epileptic agents.

Description: HALOGEN SUBSTITUTED CARBAMATE COMPOUNDS FROM 2-PHENYL-1.2-ETHANEDIOL BACKGROUND OF THE INVENTION Field of the invention The present invention relates to novel pharmaceutically useful organic compounds and more particularly, to chemically pure compounds of monocarbamates and dicarbamates of halogen substituted 2-phenyl-l,2-ethanediol represented by the structural formulas (I) and (II), wherein one enantiomer predominates and wherein the phenyl ring is substituted with one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and wherein Ri, R 2 , R3, R-i, 5 and Re are each selected from hydrogen and straight or branched alkyl groups with one to four carbons optionally substituted with a phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. The aforementioned compounds have been found to be effective in the treatment of central nervous system disorders, especially as anticonvulsants, antiepileptics, neuroprotective agents and muscle relaxants. (I) (H) Description of the prior art Racemic carbamate compounds of aryl alkyl alcohols have been known to be useful as antiepileptics and as muscle relaxants. It was reported in Toxicol. and Appl. Pharm. 2, 397-402 (1960) that when X and R are all hydrogen atoms in structural formula (I), the compound is effective as an antiepileptic agent. Dicarbamate compounds of 2-methyl-3- propyl-l,3-propanediol has been reported and their pharmacological effects have been described in J. Pharmacol. Exp. Ther., 104, 229 (1952). In US Patent No. 3,265,728, racemic carbamate compounds represented by the structural formula (UI) with a substituent on the phenyl ring has been disclosed as useful in treating central nervous system disorders. In the structural formula (DI), R 7 is carbamate or methylene carbamate, Rs is alkyl with 1-2 carbons, hydroxyalkyl with 1-2 carbons, hydroxy or hydrogen, Ra is hydrogen, alkyl with 1-2 carbons and Y is selected from the group consisting of fluorine, chlorine, bromine, iodine, methyl, methoxy, phenyl, nitro or amine groups. (HI) In US Patent No. 3,131,692, the racemic carbamate compounds represented by the structural formula (VI) have been disclosed as agents for improved central nervous system treatment with substantially reduced cholinergic side effects. In structural formula (VI), " W represents an aliphatic radical containing less than 4 carbon atoms, wherein Rio represents an aromatic radical, Rn represents hydrogen or an alkyl radical containing less than 4 carbon atoms, and Z represents hydrogen or hydroxy or alkoxy and alkyl radicals containing less than 4 carbon atoms or the radical -OC(=O)B, in which B represents an organic amine radical of the group consisting of heterocyclic, ureido and hydrazino radicals and the radical -N(Rι 2 )2 wherein R12 represents hydrogen or an alkyl group containing less than 4 carbon atoms. Moreover, at least one Z in the structural formula (VI) represents the radical -OC(=O)B. Z (VI) In US Patent No. 2,884,444, dicarbamate compounds from 2-phenyl-l,3-propanediol have been disclosed, and in US Patent No. 2,937,119 carbamate compounds such as isopropylmeprobamate have been disclosed. Some of the carbamate compounds described in the previous paragraphs are currently being used in the treatment of central nervous system disorders. However exploratory research is being conducted to identify new carbamate compounds which are even more effective for use in the treatment of various central nervous system diseases. It is a general phenomenon common to all bioactive substances that some differences are usually observed for the activities of the enantiomers when a stereogenic center is present in a bioactive molecule. Typically, by resolving a racemate mixture of bioactive compound, one enantiomer shows higher activity than the racemate while a lower activity is observed with the other enantiomer. Still one must not blindly accept the foregoing generality when developing bioactive molecules without first obtaining experimental verification, since, on occasion, unexpected results are observed due to the complex nature of biological responses to foreign substances. It is an object of the present invention to provide optically active novel carbamate compounds for therapeutic use, especially compositions containing such carbamate compounds as the active ingredient, which possess therapeutic activity in treating diseases of the central nervous system. SUMMARY OF THE INVENTION In order to achieve the foregoing object, as well as other objects of the present invention, the carbamate compounds represented by the structural formulas (I) and (II) have a chiral carbon on its benzylic position, hence there can be two optical enantiomers of the compounds represented by the structural formulas (I) and (II). Generally speaking, optical enantiomers of various compounds exhibit different pharmacological and toxicological activities, and it is the current trend in the pharmaceutical industry to develop one enantiomer with either fewer toxicological effects or better efficacy. This invention discloses the carbamate compounds represented by the structural formulas (I) and (II), in which one enantiomer is present predominantly. These compounds are useful in the treatment of central nervous system diseases, particularly as anticonvulsants, antiepileptics, neuroprotective agents and centrally acting muscle relaxants. DETAILED DESCRIPTION OF THE INVENTION This invention provides novel pharmaceutically useful optically active organic carbamate compounds represented by the structural formulas (I) and (II), wherein the phenyl ring is substituted with one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and Ri, R 2 , R 3 , Ri, Rs and Re is a functional group selected from hydrogen and straight or branched alkyl groups with one to four carbons optionally substituted with a phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. (I) (π) The compounds of the present invention possess selective pharmacological properties and are useful in treating and preventing central nervous system disorders including convulsions, epilepsy, stroke and muscle spasm. It will be apparent to those skilled in the art that the compounds of the present invention contain chiral centers. The compounds of formulas (I) and (II) contain an asymmetric carbon atom at the benzylic position, which is the aliphatic carbon adjacent to the phenyl ring. The therapeutic properties of the compounds may to a greater or lesser degree depend on the stereochemistry of a particular compound. The scope of the present invention includes pure enantiomeric forms and enantiomeric mixtures wherein one of the enantiomers of the compounds represented by the structural formulas (I) and (II) predominates. Preferably, one of the enantiomers predominates to the extent of about 90% or greater, and most preferably, about 98% or greater. The carbamate compounds represented by the structural formula (I) may be prepared by the synthetic method described in Scheme 1, a detailed description of which follows. A 2-phenyl-l,2-ethanediol with halogen substituent on the phenyl ring is reacted with diethyl carbonate in the presence of catalytic amount of sodium methoxide. The by-product methanol is removed by a vacuum distillation and the residual product is dried in vacuo. The crude reaction product is subsequently dissolved in a lower alkanol, such as methanol, and an excess amount of an amine is added to the reaction solution at room temperature to provide two regioisomeric forms of a monocarbamate of 2-phenyl-l,2-ethanediol with a halogen substituent on the phenyl ring. Regioisomeric forms of monocarbamates of 2-phenyl-l,2-ethanediol with a halogen substituent on the phenyl ring are separated by flash column chromatography providing the desired compound as the major product. Scheme 1 (I) In the structural formula (I) in Scheme 1, the phenyl ring is substituted with from one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and Ri and R 2 is a functional group selected from hydrogen and straight or branched alkyl with one to four carbons optionally substituted with phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. The carbamate compounds represented by the structural formula (II) may be prepared by the synthetic method described either in Scheme 2, in Scheme 3 or in Scheme 4, the detailed descriptions of which follow. When R3, Ri, R5 and Re are hydrogen, the desired dicarbamate compound is prepared by the synthetic method described in Scheme 2. A 2-phenyl-l,2-ethanediol with a halogen substitutent on the phenyl ring is dissolved in a solvent selected from the group consisting of acetonitrile, tetrahydrofuran and dichloromethane, and is treated with excess sodium cyanate. The resulting mixture is cooled in an ice-bath, and excess methanesulfonic acid is added slowly. When the starting diol is not detected by thin layer chromatography, the reaction mixture is neutralized with aqueous sodium hydroxide and extracted with methylene chloride. The organic extract is dried, filtered, and concentrated and the desired compound is purified by flash column chromatography. Scheme 2 <π) In structural formula (II) in Scheme 2, the phenyl ring is substituted with from one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms. When the carbamate units in a dicarbamate represented by structural formula (II) are identical, that is when R3 = Rs and Ri = Re, the desired compound is prepared by synthetic method described in Scheme 3. A 2-phenyl-l,2-ethanediol with a halogen substituent on the phenyl ring is dissolved in dichloromethane and is treated with about 2 equivalents of carbonyl diimidazole. The resulting mixture is stirred until the starting material is not observed by thin layer chromatography analysis, and the mixture is treated with excess amount of amine (RaR 4 NH). It takes typically more than 24 hours to complete the reaction. After a routine aqueous wash, the crude reaction product is purified by flash column chromatography to provide the desired product. Scheme 3 (II) In structural formula (II) in Scheme 3, the phenyl ring is substituted with from one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and R3 and Ri may be a functional group selected from hydrogen and straight or branched alkyl with one to four carbons optionally substituted with a phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. When the carbamate units in a dicarbamate represented by the structural formula (II) are different, the desired compound is prepared from a corresponding monocarbamate represented by the structural formula (I) which was prepared by the synthetic method described in Scheme 1, using the synthetic method described in Scheme 4. A 2-phenyl-l,2-ethanediol monocarbamate from a group of compounds represented by the structural formula (I) is treated with about 1 equivalent of carbonyl diimidazole. The resulting mixture is stirred until the starting material is not observed by thin layer chromatography analysis, and the mixture is treated with an excess amount of amine (RsRβNH). It takes typically more than 24 hours to complete the reaction. After a routine aqueous wash, the crude reaction product is purified by flash column chromatography to provide the desired product. Scheme 4 (I) (fl) In structural formulas (II) in Scheme 4, the phenyl ring is substituted with from one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and R_, R 2 , Rs and Re are a functional group selected from hydrogen and straight or branched alkyl with one to four carbons optionally substituted with phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. In utilizing the compounds of the present invention for the treatment of diseases of the central nervous system, particularly the treatment of convulsions, epilepsy, stroke and muscle spasm, it is preferred to administer the compounds orally. Since the compounds are well absorbed orally, it usually will not be necessary to resort to parenteral administration. For oral administration, the present carbamate compounds are preferably combined with a pharmaceutical carrier. The ratio of the carrier to the compounds of the present invention is not critical to achieve the effects of the medicine on the central nervous system, and they can vary considerably, depending on whether the composition is to be filled into capsules or formed into tablets. In tableting, it is usually desirable to employ at least as much pharmaceutical carrier as the pharmaceutically active ingredients. Various edible pharmaceutical carriers or mixtures thereof can be used. Suitable carriers, for example, are a mixture of lactose, dibasic calcium phosphate and corn starch. Other pharmaceutically acceptable ingredients can be further added, including lubricants such as magnesium stearate. The therapeutic use of the compounds claimed in the present invention as anticonvulsants has been proven by the "Maximal ElectroShock (MES)" test, which is a well-established pharmacological screening method for anticonvulsants against partial seizures, and the results are presented in Table I. The procedure employed in the MES test for anticonvulsants follows. The compound dosing solutions were prepared in saline, and the subject, namely, mice (CF-1 strain), were dosed orally. After the designated number of hours, maximal electroshock was induced in mice via corneal electrodes using IITC Life Science model 11 A Shocker at 50mA-60Hz for 0.2 second. Upon inducing maximal electroshock, the elimination of hindlimb tonic extension was considered as providing evidence of the protection by an anticonvulsant. Median efficacy dose (ED50) levels were determined using three different dose levels with at least 6 mice in each group. Compounds with smaller ED50 value are more potent as anticonvulsants. Table I Dunham and Miya method (Dunham, N.W. and Miya, T.S.: A note on a simple apparatus for detecting neurological deficit in rats and mice. J. Amer. pharm. Ass., sci Ed. 46, 208-209 (1957)) was employed for the median neurotoxic dose (TD50) test. Dunham and Miya (1957) devised a simple and effective method for determining the neurological deficit or neurotoxicity of a test compound in mice and rats based on the ability of the animal to remain on a rotating rod. TD50 is defined as the dose which causes 50% of the animals to fail the rotorod test, i.e., fall more than once in a one-minute test period. The ratio of the TD50 to the ED50 is called the Protective Index, and serves as a useful parameter when comparing pharmacological potency and neurotoxicity. The results of the present investigation are presented in Table II. Table π A better understanding of the present invention may be obtained in light of following examples which are set forth to illustrate, but art not to be construed to limit, the present invention. The diols used in the syntheses of carbamate compounds were prepared by a dihydroxylation reaction from their corresponding styrenic compound. In preparations of optically active diols, Shai less's asymmetric dihydroxylation catalysts were used. EXAMPLE I ( DL ) - ( 2- ( 2-ChloroDhen y l ) -2-carbamoyloxyethyl)oxocarboxamide: ( • reneral procedure for preparing unsubstituted dicarbamate compounds (DL)-l-o-Chlorophenyl-l,2-ethanediol was dissolved in tetrahydrofuran (115mL) and sodium cyanate (9.0g) and methanesulfonic acid (9.5mL) was added in an ice bath. The resulting reaction mixture was stirred for 18 hours, extracted with tetrahydrofuran-dichloromethane mixture, washed with 5% aqueous sodium hydroxide, dried over sodium sulfate, filtered, concentrated and purified by flash column chromatography to yield a white solid. Analytically pure (DL)-(2-(2-chlorophenyl)- 2-carbamoyloxyethyl) oxocarboxamide (m.p. 190 TJ) was obtained after recrystallization from ethanolether mixture. EXAMPLE π (R)-(2-(2-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (R)-(2-(2-CWorophenyl)-2-carb-unoyloxyethyl)oxocarboxamide (2.1g, yield 46%, m.p. 172-174 TC, [ α ] D =84.9 (c=2.70, DMF)) was prepared using the same synthetic method described in Example I, except that (R)-l-o-chlorophenyl-l,2-ethanediol (3.0g) was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE DI ( S) - ( 2- ( 2- Chlorophenyl) -2- carbamoy loxyethy Doxocarboxamide (S)-(2-(2-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (1.6g, yield 35%, m.p. 167-169 Xl, [ β ] D =-84.1 (c=2.27, DMF)) was prepared using the same synthetic method described in Example I, except that (. )-l-o-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o- chlorophenyl- 1 , 2-ethanediol. EXAMPLE IV ( DL) - (2- ( 3- Chlorophenyl) - 2-carbamoyloxyethy Doxocarboxamide (DL)-(2-(3-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (2.41g, yield 80%, m.p. 188-190 Tl) was prepared using the same synthetic method described in Example I, except that (DL)-l-m-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE V ( DL) - (2- (4- Chloropheny 1)- 2-carbamoyloxy ethyDoxocarboxamide (DL)-(2-(4-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (1.97g, yield 38%, m.p. 146- 148 TJ) was prepared using the same synthetic method described in Example I, except that (DL)-l-p-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE VI (R)-(2-(4-Clτlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (R)- (2-(4-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (2.53g, yield 84%, m.p. 178-180 t, [ α] D =-24.38 (c=2.60, MeOH)) was prepared using the same synthetic method described in Example I, except that (R)-l-p-chlorophenyl-l,2-ethanediol was used instead of ( DL)- 1 -o -chlorophenyl- 1 ,2-ethanediol. EXAMPLE VII (S)-(2-(4-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (S ) - ( 2- (4- Chloropheny 1)- 2-carbεunoyloxyethy Doxocarboxamide ( .04g, yield 68%, m.p. 177-179 tj, [ a ] υ =25.56 (c=2.75, MeOH)) was prepared using the same synthetic method described in Example I, except that (S)-l-p-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE Vm (DL)-(2-(2,6-Dichlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (DL)-(2-(2 > 6-Dichlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (1.71 g, yield 40%, m.p. 160-162TJ) was prepared using the same synthetic method described in Example I, except that (DL)-l-(2,6-dichlorophenyl)-l,2 -ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE DC (R)-(2-(2,6-Dichlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (R)-(2-(2,6-Dichlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (7.40g, yield 52%, [ a ] D =36.01 (c=2.58, MeOH)) was prepared using the same synthetic method described in Example I, except that (R)-l-(2,6-dichlorophenyl)-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE X (R)-(2-(2-Chlorophenyl)-2-(N-methylcarbamoyloxyethyl)oxocarboxamide: General procedure for preparing monosubstituted dicarbamate compounds l, -Carbonyldiimidazole (l.Og, 6.12 mmol) was added to a solution of (R)-(2-(2-chlorophenyl-2-hydroxyethyl)oxocarboxamide (1.2g, 5.56 mmol) in tetrahydrofuran (4mL) at 5ΪJ. The reaction mixture was allowed to come to room temperature and stirred 45 min. Methylamine (5.6mL of a 2 M solution in THF) was added at 5"C. The reaction mixture was stirred for 18 hr at room temperature, extracted with ethyl acetate, washed with 0.5N aqueous hydrochloric acid, saturated sodium bicarbonate and brine. The extracts were dried over sodium sulfate, filtered, concentrated and purified by flash chromatography to yield a white solid (1.4g, yield 93%, m.p. 128-130 TJ, EXAMPLE XI (R)-(2-(2-Chlorophenyl)-2-(N-isopropylcarbamoyloxyethyl)-oxocarboxamide (R)-(2-(2-Chlorophenyl)-2-(N-isopropylcarbamoyloxyethyl)oxo-carboxami de (l.Og, yield 62%, m.p. 163-165TJ, [ cr ] D =3.99 (c=2.10 f MeOH)) was prepared using tlie same synthetic method described in Example X, except that isopropylamine was used instead of methylamine. EXAMPLE XT! (R)-(2-(2-Cl lorophenyl)-2-(N-cyclopropylcarbamoyloxyethyl)-oxocarboxamide (R)-(2-(2-Clτlorophenyl)-2-(N-cyclopropylcarbamoyloxyethyl)oxo-carboxa mide (1.60g, yield 96%, m.p. 111-113ΪJ, [ ff ] D =2.39 (c=2.25, MeOH)) was prepared using the same synthetic method described in Example X, except that cyclopropylamine was used instead of methylamine. EXAMPLE Xm (R)-N-Methyl(2-(2-chlorophenyl)-2-(N-methylcarbamoyloxyethyl)- oxocarboxamide: General procedure for preparing N,N' -disubstituted dicarbamate compounds A solution of (R)-2-chlorophenyl-l,2-ethanediol (2.0g, 11.6 mmol) in tetrahydrofuran was added dropwise to a suspension of l, -carbonyldiimidazole (4.13g, 25.5 mmol) in tetrahydrofuran (10 mL) at 5\ over a 20 min period. After stirring 1 hr at room temperature, methylamine (23.2 mL, 2 M solution in THF, 46.4 mmol) was added at 5V. After stirring 18 hr at room temperature, the reaction mixture was concentrated in vacuo and purified by flash chromatography to give a white solid (2.03g, 61%, m.p. 152-154 TJ). EXAMPLE XIV (R)-N-Isopropyl(2- ( -chlorophenyl) -2- (N-isopropylcarbamoy loxyethyl) oxocarboxamide (R)-N-Isopropyl(2-(2-chlorophenyl)-2-(N-isopropylcarbamoyloxyethyl)oxo carboxamide (3.50g, yield 88%, m.p. 151-1531, [ α ] D =1.33 (c=2.63, MeOH)) was prepared using the same synthetic method described in Example XILI, except that isopropylamine was used instead of methylamine. EXAMPLE XV (R)-N-Phenyl(2-(2-chlorophenyl)-2-(N-phenylcarbamoyloxyethyl)- oxocarboxamide (R)-N-Phenyl(2-(2-chlorophenyl)-2-(N-phenylcarbamoyloxyethyl)-oxocar boxamide (2.74g, yield 57%, m.p. 46-48V) was prepared using the same synthetic method described in Example XHI, except that aniline was used instead of methylamine. EXAMPLE XVI (R)-N-Benzyl(2-(2-chlorophenyl)-2-(N-benzylcarbamoyloxyethyl)- oxocarboxamide (R)-N-Benzyl(2-(2-chloiOphenyl)-2-(N-benzylcarb£imoyloxyethyl)-oxocar boxamide (2.88g, yield 76%, m.p. 80-82 TJ) was prepared using the same synthetic method described in Example XIII, except that benzylamine was used instead of methylamine. EXAMPLE XVπ (DL)-(2-(2-chlorophenyl)-2-hydroxyethyl)oxocarboxamide: (ieneral procedure for preparing monocarbamate compounds In a 50mL round bottom flask equipped with vacuum distillation apparatus, (DL)-l-o-chlorophenyl-l,2-ethanediol (10.98g), diethyl carbonate (10.25mL) and sodium methoxide (305mg) were placed and the resulting mixture was heated in an oil bath up to 135 with magnetic stirring. The by-product, ethyl alcohol was collected in a receiver flask. After collecting approximately lOmL of ethanol, the residual ethyl alcohol remaining in the reaction mixture was removed by vacuum distillation. The reaction mixture was cooled to room temperature, dissolved in dichloromethane (40mL), washed with brine (15mL), dried over anhydrous sodium sulfate, filtered and then concentrated in vacuo to produce (DL)-l-o-chlorophenyl-l,2-ethanediol carbonate (12.58g, yield 100%). In a 200mL round bottom flask equipped with a magnetic stirrer, approximately 12mL of liquid ammonia was condensed at -78 V, and (DL)-l-o-chlorophenyl-l,2-ethanediol carbonate (6.0g) in methanol (200mL) was added slowly. The reaction mixture was slowly warmed to room temperature and was stirred at room temperature for another hour, and then concentrated in vacuo. (DL)-(2-(2-Chlorophenyl)-2-hydroxyethyl) oxocarboxamide (1.97g, yield 30%, rap. 100 V) was obtained after a chromatographic purification. EXAMPLE XVπi (R)-(2-(2-chlorophenyl)-2-hydroxyethyl)oxocarboxamide (R)-(2-(2-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (3.35g, yield 45%, m.p. 13 V , [ ]u-63.9 (c-2.22, methanol)) was prepared using the same synthetic method described in Example XVII, except that (R)-o-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE XLX (S)-(2-(2-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (S)-(2-(2-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (3.89g, yield 52%, m.p. 133 V, [ α ]n=64.9 (c=2.69, methanol)) was prepared using the same synthetic method described in Example XVII, except that (S)-o-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol. EXAMPLE XX (DL)- (3-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (DL)-l-m-Chloropheny-l,2-ethanediol carbonate was prepared using the same synthetic method described in Example XVII, except that (DL)-l-m-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-o-chlorophenyl-l,2-ethanediol in a quantitative yield. In a 250mL round bottom flask equipped with a magnetic stirrer, (DL)-l-m-chlorophenyl-l,2-ethanediol carbonate (10.95g) was dissolved in methanol (60mL) and the mixture was cooled in an ice bath. Ammonium hydroxide (30mL, 28-30%) was added to the mixture and the mixture was stirred at room temperature for 1 hour or until the reaction was completed as evidenced by thin layer chromatography. Excess ammonium hydroxide and methanol were removed in vacuo to yield a white solid. (DL)-(3-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (1.25g, yield 10%, m.p. 90 V) was purified by flash column chromatography. EXAMPLE XXI ( R) - ( 3- Chloropheny 1) - 2-hydroxyethy Doxocarboxamide (R)-(3-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (1.77g, 45%, m.p. 114-116 V) was prepared using the same synthetic method described in Example XX, except (R)-l-m-chlorophenyl- 1,2-ethanediol was used instead of (DL)-l-m-chlorophenyl-l,2- ethanediol. EXAMPLE XXπ ( S) - (3-ChlorophenyD-2-hydroxyethyl)oxocarboxamide (S)-(3-Chlorophenyl)-2-carbamoyloxyethyl)oxocarboxamide (1.36g, yield 25%, m.p. 117-11 V, [ -. ] =12.88 (c=2.30, MeOH)) was prepared using the same synthetic method described in Example XX, except (S)-l-m-chlorophenyl-l,2-ethanediol was used instead of (DL)-l-m-chlorophenyl-l,2-ethanediol. EXAMPLE XXIH (R)-(4-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (R)-(4-chlorophenyl)-2-hydroxyethyl)oxocarboxamide (1.15g, yield 31%, m.p. 110-112 V) was prepared using the same synthetic method described in Example XX, except (R)-l-p-chlorophenyl- 1,2-ethanediol was used instead of (DL)-l-m-chlorophenyl-l,2- ethanediol. EXAMPLE XXIV (S)-(4-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (S)-(4-Chlorophenyl)-2-hydroxyethyl)oxocarboxamide (1.14g, yield 30%, m.p. 110-112 , [ β ] =18.62 (C=2.40, MeOH)) was prepared using the same synthetic method described in Example XX, except (S)-l-p-chlorophenyl-l,2-ethanediol was used instead of (DL) - 1-m-chlorophenyl- 1,2-ethanediol. EXAMPLE XXV (DL)-(2-(2,6-dichlorophenyD-2-hydroxyethyl)oxocarboxarnide (DL)-(2-(2,6-dichlorophenyD-2-hydroxyethyDoxocarboxamide (1.05g, yield 43%, m.p. 120-122V) was prepared using the same synthetic method described in Example XX, except (DL)-2,6- dichlorophenyl-l,2-ethanediol was used instead of (DL)-l-m- chlorophenyl- 1,2-ethanediol.

Claims: WHAT IS CLAIMED IS: 1. Pure enantiomeric forms, as well as enantiomeric mixtures wherein one enantiomer of 2-phenyl-l,2-ethanediol carbamate compounds represented by the structural formula (I) predominates, and wherein the phenyl ring is substituted witli from one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and Ri and R 2 , are functional groups selected from hydrogen and straight or branched alkyl group with from one to four carbons optionally substituted with a phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. (I) 2. The compound of claim 1, wherein one enantiomer is present to the extent of about 90% or greater. 3. The compound of claim 1, wherein one enantiomer is present to the extent of about 98% or greater. 4. The compound of claim 1, wherein Ri and R 2 are both hydrogen. 5. The compound of claim 1, wherein Ri and R 2 are both hydrogen and the phenyl ring is substituted with from one to five chlorine atom. 6. The compound of claim 1, wherein Ri and R 2 are both hydrogen and the phenyl ring is substituted with a chlorine atom. 7. The compound of claim 1, wherein Ri and R2 are both hydrogen and the phenyl ring is substituted with a chlorine atom at the ortho position. 8. A pharmaceutical composition for treating disorders of the central nervous system which comprises as an active ingredient an effective amount for treating disorders of the central nervous system of a compound of Formula (1) as defined in claim 1 and a pharmaceutically acceptable carrier. 9. The composition of claim 8, wherein the central nervous system disorder being treated is selected from the group consisting of convulsions or epilepsy. 10. A method of eliciting an anti-convulsive or anti-epileptic effect in mammal which comprises administering the composition of claim 9 to a mammal in need of anti-convulsive or antiepileptic therapy. 11. Pure enantiomeric forms, as well as enantiomeric mixtures wherein one enantiomer of 2-phenyl-l,2-ethanediol carbamate compounds represented by the structural formula (II) predominates, and wherein the phenyl ring is substituted with from one to five halogen atoms selected from fluorine, chlorine, bromine or iodine atoms, and R3, Rj, s and Re are functional groups selected from hydrogen and straight or branched alkyl groups with from one to four carbons optionally substituted with phenyl group with substituents selected from the group consisting of hydrogen, halogen, alkyl, alkyloxy, amino, nitro and cyano. (DO 12. The compound of claim 11, wherein one enantiomer is present to the extent of about 90% or greater. 13. The compound of claim 11, wherein one enantiomer is present to the extent of about 98% or greater. 14. The compound of claim 11, wherein R3, R 4 , Rs and R 6 are all hydrogen. 15. The compound of claim 11, wherein R3, Ri, R5 and Re are all hydrogen and the phenyl ring is substituted with one to five chlorine atom. 16. The compound of claim 11, wherein R3, Rt, R5 and Re are all hydrogen and the phenyl ling is substituted with a chlorine atom. 17. The compound of claim 11, wherein R3, Rt, R5 and Re are all hydrogen and the phenyl ring is substituted with a chlorine atom at the ortho position. ° 18. A pharmaceutical composition for treating disorders of the central nervous system which comprises as an active ingredient an effective amount for treating disorders of the central nervous system of a compound of Formula (II) as defined in claim 11 and a pharmaceutically acceptable carrier. 19. The composition of claim 18, wherein the central nervous system disorder being treated is selected from the group consisting of convulsions or epilepsy. 20. A method of eliciting an anti-convulsive or anti-epileptic effect in a mammal which comprises administering the composition of claim 19 to a mammal in need of anti- convulsive or anti-epileptic therapy.

Inventors: CHOI YONG MOON, KIM MIN WOO, PARK JEONG HAN, CHOI, YONG, MOON, KIM, MIN, WOO, PARK, JEONG, HAN
Applicants: YUKONG LTD, YUKONG LIMITED
Application year: 1997
Main classification: C07C271
IPC codes: A61K31, C07C271