WO2007078176A1

WO2007078176A1 - The method of making optically active 2-chloromandelic acid esters and 2-chloromandelic acids by enzymatic method

Info

Publication number: WO2007078176A1
Application number: PCT/KR2007/000085
Authority: WO
Inventors: Soon Ook Hwang; Sun Ho Chung
Original assignee: Enzytech Ltd
Current assignee: Enzytech Ltd
Priority date: 2006-01-05
Filing date: 2007-01-05
Publication date: 2007-07-12
Anticipated expiration: 2008-07-05
Also published as: KR100722155B1

Abstract

The present invention relates to process for the preparation of optically active 2-chloromandelic acid esters represented by the general formula 2 and optically active 2-chloromandelic acids represented by the general formula 2 which are used intensively as important chiral intermediates. In more detail, this invention relates to the process for preparing optically active 2-chloromandelic acid esters and optically active 2-chloromandelic acids by stereospecific hydrolysis of racemic 2-chloromandelic acid ester using lipases or lipase-producing microorganisms in the aqeous phase or organic phase including aqeous solvent. The method of making optically active 2-chloromandelic aicd esters and their acids is usful in the practical process because production of seperation of compounds with high optical purity are easy.

Description

Description THE METHOD OF MAKING OPTICALLY ACTIVE

2-CHLOROMANDELIC ACID ESTERS AND 2-CHLOROMANDELIC ACIDS BY ENZYMATIC METHOD

Technical Field

[1] The present invention relates to process for the preparation of optically active

2-chloromandelic acid esters and their acids by enzymes or microorganisms. In more detail, optically active 2-chloromandelic acid ester represented by the general formula 2 and optically active 2-chloromandelic acid represented by the general formula 3 are prepared from racemic 2-chloromandelic acid ester represented by the general formula 1 in scheme 1 by hydrolases or hydrolase-producing microorganisms.

[2] [ Scheme 1]

[3]

[4] In scheme 1, R is selected from substituted or unsubstituted alkyl groups or alkenyl groups wherein the alkyl contains from C i to C , benzyl groups, cycloalkyl groups comprising from C 3 to C 6 , substituted or unsubstituted arylalkyl groups, and substituted or unsubstituted heteroarylalkyl groups.

[5] Optically active 2-chloromandelic acid esters are valuable chiral intermediates for synthesizing (S)-clopidogrel bisulfate with platelet aggregation inhibiting activity. Tosylated or mesylated compounds can be converted to optically active 2-chlorostyrene oxide which is used for important pharmaceutical intermediates by epoxydation (Korea Patent 10-2005-0035057).

[6]

Background Art

[7] Noda Hirobumi et al.(JP-0072644) prepared a diastereomer salt by reacting racemic 2-chloromandelic acid with an optically active N-benzyl-1-phenylethylamine as an optical resolution agent and obtained (R)-2-chloromandelic acid by acidification of a diastereomer salt. However, this method needs recrystallization process. Likewise, Hyoda Toshiharu et al.(JP-0114737) obtained (R)-2-choloromandelic acid using optically active alanine as an optical resolution agent. [8] North Michael et al.(W0 02/10095 A3) prepared (R)-O-acetyl-cyanohydrin by cyanation and acetylation from 2-chlorobenzaldehyde using chiral ligand and chiral catalyst and obtained(R)-2-chloromandelic acid by hydrolysis of (R)-O-acety 1- cyanohydrin. This process needs recrystallization step and has some problem during the reaction.

[9] On the other hand, there are several methods to prepare optically active

2-chloromandelic acid using enzyme and microorganisms.

[10] Kim et al.(KP 10-2004-0063264) prepared (R)-2-chloromandelic acid and their ester using Baker's yeast. 2-chloromandelic acid alkyl ester was produced from 2-chloromandelic acid and converted to alkyl 2-chloro-benzoylformate, By asymmetic reduction using Baker's yeast, methyl 2-chloro-benzoylformate, ethyl 2-chloro-benzoylformate and butyl 2-chloro-benzoylformate were converted to 2-chloromandelic acid alkyl esters. Their converion was 99.9 %, 88.5%, 99.7 % and optical purity was 98.45, 98.5, 98.4 e.e%, respectively. This process has a disadvartage because of many reaction steps.

[11] Korea Patent( 10-2005-0035057) presents the method of preparing

(R)-2-chloromandelic acid ester(100 e.e%) and (S)-2-chloromandelic acid diester by esterifiction of racemic 2-chloromandelic acid ester using lipase in organic phase. However, this method has some problem in seperation and recovery after reaction.

[12] Van Langen et al. (Organic Process Research & Development, 2003, 7, 828-831) synthesized 2-(2-chlorophenyl)-2-hydroxyacetonitrile from 2-chlorobenzaldehyde using oxynitrilase and obtained (R)-2-choloromandelic acid (99 e.e%) by hydrolysis and recrystallization.

[13]

Disclosure of Invention Technical Problem

[14] With this in mind, We, inventors developed the method which is simple and easy in product recovery comparing to the conventional methods. The present invention provides the new method of preparing of optically active 2-chloromandelic acid esters and their acids by hydrolases or hydrolase-producing microorganisms. And this method can be used in practical process because seperation and recovery of 2-chloromandelic acid esters and their acids produced by this invention are easier. Technical Solution

[15] The invention is explained in more detail as follows. As previously stated, this invention includes the process for preparing optically active 2-chloromandelic acid ester and optically active 2-chloromandelic acid by stereospecific hydrolysis of racemic 2-chloromandelic acid ester using hydrolases or hydrolase-producing mi- croorganisms. And optically active 2-chloromandelic acid ester is converted to optically active 2-chloromandelic acid by hydrolysis using agents such as sodium hydroxide.

[16] In preparing optically active compounds, hydrolases such as CAL A(Novozym

735), CAL B(Novozym 435), alcalase, and protease A or hydrolase-producing microorganisms are used as biocatalysts.

[17] In this invention, reactants and products were analyzed as belows.

[18] Racemic 2-chloromandelic acid ester was determined using gas chromatography (Donam Instrument Inc., Model 6200) equipped with HP-FFAP column(Agilent, Inc., 3O m X 0.53 mm). The oven temperature was maintained initially at 100 ⁰C for 5 min and then raised at the rate of 20 °C/min to 220 ⁰C, and maintained for 10 min. Helium gas was used as carrier and column head pressure was maintained at 6 psi, and compounds were detected using FID at 220 ⁰C. In this condition, the typical retention time of methyl 2-chloromandelate, ethyl 2-chloromandelate and butyl 2-chloromandelic acid was 15.31 min, 14.89 min and 17.28 min, respectively.

[19] Optically active 2-chloromandelic acid ester was determined by HPLC(Lab

Aliance, Model 201) equipped with chiral column AD-H(Daicel). Hexane and isopropyl alcohol mixture(90:10) used as mobile phase and flow rate was 0.7 ml/min, and the absorbance was 220 nm. The typical retention time of the compound in this condition was as follows:

[20] methyl (S)-2-chloromandelate - 12.71 min

[21] methyl (R)-2-chloromandelate - 13.93 min

[22] ethyl (S)-2-chloromandelate - 12.00 min

[23] ethyl (R)-2-chloromandelate - 13.95 min

[24] butyl (S)-2-chloromandelate - 10.36 min

[25] butyl (R)-2-chloromandelate - 12.06 min

[26]

[27] The following specific examples are intended to be illustrative of the invention and should not be construed as limiting the scope of the invention as defined by appended claims.

[28]

[29] Example 1. Preparing of racemic alkyl 2-chloromandelate

[30]

[31] 2g of racemic 2-chloromandelic acid was added to 40ml of methanol and 35 % HCl solution. The reaction was carried out at 75 ⁰C for 3 hours. The reaction mixture was neutralized and racemic methyl 2-chloromandelate was gained by solvent extraction and distillation under reduced pressure. Racemic ethyl 2-chloromandelate and butyl 2-chloromandelate were synthesized using ethanol or buthanol, respectively instead of methanol. And the products were confirmed by nuclear magnetic resonance(Burker, Model DRS300).

[32] Methyl 2-chloromandelate [33] ¹H-NMR(CDCl , 300MHz) δ(ppm) = 3.76(s, 3H), 5.57(s, IH), 7.27(m, 2H), 7.39(m, 2H)

[34] Ethyl 2-chloromandelate [35] ¹H-NMR(CDCl , 300MHz) δ(ppm) = 1.21(t, 3H), 4.21(m, 2H), 5.54(s, IH), 7.27(m, 2H), 7.38(m, 2H)

[36] Butyl 2-chloromandelate [37] ¹H-NMR(CDCl , 300MHz) δ(ppm) = 0.83(t, 3H), 1.23(m, 2H), 1.54(m, 2H), 4.16(t, 2H), 5.56(s, IH), 7.25(m, 2H), 7.38(m, 2H)

[38] [39] [40] Example 2-3. Preparing of optically active methyl 2-chloromandelate by hydrolysis [41] [42] Racemic methyl 2-chloromandelate(l %(v/v)) prepared in Example 1 was added to 5 ml of 0.1 M potassium phosphate buffer(pH 7.0) and the reaction was carried out at 30 ⁰C using enzymes (1 %(w/v)). The reaction mixture was extracted with ethyl acetate and analyzed by above-mentioned method. The results are shown in Table 1.

[43] Table 1

[44] [45] Example 4-7. Preparing of optically active ethyl 2-chloromandelate by hydrolysis [46] [47] Instead of racemic methyl 2-chloromandelate used in Example 2, ethyl 2-chloromandelate was used as a reactant and the results are shown in Table 2.

[48] Table 2

[49] [50] Example 8. Preparing of optically active butyl 2-chloromandelate by hydrolysis [51] [52] Instead of racemic methyl 2-chloromandelate used in Example 2, butyl 2-chloromandelate was used as a reactant and CAL B was used as a biocatalyst. The reaction was carried out for 48 hours and butyl (R)-2-chloromandelate was obtained with 76 e.e% (conversion 93.1%).

[53] [54] Example 9. Preparing of optically active (R)-chloromandelic acid [55] [56] Ethyl (2)-2-chloromandelate (99 ee%) was prepared from racemic ethyl 2-chloromandelate by hydrolysis using CAL B. Ethyl (R)-2-chloromandelate was dissolved in methanol and 10 %(w/v) sodium hydroxide solution was added to this reaction mixture. After reaction at room temperature, reaction mixture was acidified to pH 1 and white solid was obtained by solvent extraction using t-butyl methyl ester(t-BME). (R)-2-chloromandelic acid (99e.e%) was obtained.

[57]

Industrial Applicability [58] In accordance with Examples 2-9, optically active 2-chloromandelic acid ester can be produced easily by this invention, and the product with high optical purity was obtained. Also, it is easy to recover optically active esters and optically active 2-chlromandelic acids after reaction. Therefore, this method is an useful process on the industrial scale.

[59] [60]

Claims

[1] A process preparing for optically active 2-chloromandelic acid esters represented by the general formula 2 and optically active 2-chloromandelic acids represented by the general formula 3 by hydrolysis from racemic 2-chloromandelic acid esters represented by the general formula 1 using hydrolases or hydrolase- producing microorganisms as biocatalysts. [Scheme 1]

In scheme 1, R is selected from substituted or unsubstituted alkyl groups or alkenyl groups wherein the alkyl contains from C i to C , benzyl groups, cycloalkyl groups comprising from C to C , substituted or unsubstituted

3 6 arylalkyl groups, and substituted or unsubstituted heteroarylalkyl groups. [2] A process prepaing for optically active 2-chloromandelic acid esters and optically active 2-chloromandelic acids according to claim 1, wherein the biocatalyst are lipase, esterase, protease or these enzyme-producing microorganisms.