JP2000023693A - Production of optically active 2-acetylthio-3- phenylpropionic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain the subject optically active phenylpropionic acid, in high yield, that can be used as a starting material for an antihypertensive agent by hydrolyzing an enantiomer mixture of 2-acetylthio-3-pheny]-propionic ester asymmetrically at their ester bonds. SOLUTION: An enantiomer mixture of 2-acetylthio-3-phenyl-propionic ester represented by formula I (R is a 1-10C alkyl) or formula II is hydrolyzed by an enzyme that can asymmetrically hydrolyze the ester bond in the 2- acetylthio-3-phenylpropionic ester to give an optically active 2-acetylthio-3- phenylpropionic acid in high yield. This chemical is useful as an intermediate for an optically active compound that is utilized as a medicine, for example, an ACE inhibitor (antihypertensive agent).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing optically active 2-acetylthio-3-phenylpropionic acid.

[0002]

2. Description of the Related Art 2-Acetylthio-3-phenylpropionic acid is a useful intermediate of an optically active compound used in pharmaceuticals. For example, it is used in the production of ACE inhibitors (hypertensive agents).

[0003] Therefore, a method for industrially producing these with high optical purity is desired. However, in the conventional production method, only the optically active (R) -form or (S) -form is used as a starting material, which is reacted by an organic chemical reaction to produce optically active 2-acetylthio-3-phenylpropionic acid. Was the way to do it. In this case, it is necessary to use only one of the optically active isomers as a starting material. Therefore, usually, it is necessary to separate the enantiomeric mixture into an optically active (R) or (S) isomer in advance. There were problems with the rate and economics. Therefore,
There has been a demand for a method for directly and efficiently producing optically active 2-acetylthio-3-phenylpropionic acid using an enantiomeric mixture as a starting material.

JP-A-10-14590 discloses the production of optically active 2-substituted-3-phenylpropionic acids having a substituent other than fluorine, an alkylsulfonyloxy group or an arylsulfonyloxy group, and esters thereof. A method is disclosed. However, the present invention relates to an optically active 2-substituted compound in which the substituent has an acetylthio group.
It differs in that it is 3-phenylpropionic acid. Furthermore, when an enzymatic reaction is carried out using a compound having an acetyl group in the molecule, such as an acetoxy group or an acetylthio group, the acetyl group is very susceptible to hydrolysis and generally causes deacetylation. is there.

Therefore, when an enzymatic reaction is carried out on a substrate having both an acetylthio group and a carboxylic acid ester, an optically active product can be obtained by selectively hydrolyzing only the carboxylic acid ester without deacetylation. Was considered difficult.

[0006]

An object of the present invention is to efficiently produce optically active 2-acetylthio-3-phenylpropionic acid having high optical purity.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that 2-acetylthio-3
A predetermined lipase is allowed to act on the enantiomeric mixture of phenylpropionic acid to form either the (R) -form or the (S) -form in the enantiomeric mixture;
The inventors have found that the ester bond of -acetylthio-3-phenylpropionic acid ester can be selectively asymmetrically hydrolyzed, thereby completing the present invention.

That is, the present invention provides 2-acetylthio-3-phenylpropionic acid represented by the following general formula (1) or (2), wherein R represents an alkyl group having 1 to 10 carbon atoms. The enantiomeric mixture of the ester is
-Acetylthio-3-phenylpropionic acid ester is hydrolyzed with an enzyme capable of asymmetric hydrolysis to give an optically active 2-acetylthio-3-phenylpropione represented by the following general formula (3) or (4): This is a method for producing optically active 2-acetylthio-3-phenylpropionic acid, which gives an acid.

[0009]

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[0010]

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[0011]

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[0012]

Embedded image Further, the present invention is the above-mentioned production method, wherein R in the general formulas (1) and (2) is an alkyl group having 1 to 4 carbon atoms.

[0013] Further, the present invention provides the above-mentioned enzyme, wherein
The method according to the above, wherein the lipase is derived from a microorganism belonging to the genus Rhizomucor, the genus Alcaligenes or the genus Candida.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The present invention relates to the following general formula (1) or (2):
(Wherein, R represents an alkyl group having 1 to 10 carbon atoms). An enantiomeric mixture of 2-acetylthio-3-phenylpropionic acid ester represented by the formula: The bond is hydrolyzed by an enzyme capable of asymmetric hydrolysis to obtain an optically active 2-acetylthio-3-phenylpropionic acid represented by the following general formula (3) or (4). This is a method for producing 3-phenylpropionic acid.

The enantiomeric mixture of 2-acetylthio-3-phenylpropionate used in the present invention is a compound represented by the above general formula (1) or (2). In the general formula (1) or (2), R is a linear or branched alkyl group having 1 to 10 carbon atoms. Preferably it is a C1-C6 alkyl group, More preferably, it is a C1-C4 alkyl group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc. The enantiomeric mixture refers to a mixture of the (R) -form and the (S) -form which are enantiomers of 2-acetylthio-3-phenylpropionate. Also,
Although the ratio is not particularly limited, usually, it is preferable to use a racemic form which is an equal mixture of the (R) form and the (S) form,
It is preferable from the viewpoint of economy.

In the present specification, optically active 2-
Acetylthio-3-phenylpropionic acid is defined as (S) 2-acetylthio-3-phenylpropionic acid or (R) 2-acetylthio-3-phenylpropionic acid represented by the above general formula (3) or (4). Point to each. However, the optical purity of each optically active substance is not necessarily 100%
e. e. And it may be a mixture of the (R) form and the (S) form.

As the enzyme used in the present invention, an enzyme derived from a microorganism can be appropriately used, but is not limited to an enzyme derived from a microorganism, and α-chymotrypsin derived from bovine pancreas, esterase derived from pig liver, and the like. Enzymes from various animals can also be used.

Examples of microorganism-derived enzymes include Rhizopus, Mucor, and Rhizomucol.
(Rhizomucor) genus, Alcaligenes
Examples include lipases derived from microorganisms belonging to the genus and Candida, and it is preferable to use lipases derived from these microorganisms. As these lipases, lipases derived from microorganisms belonging to the genus Mucor (eg, LIPO
ZYME IM, manufactured by Novo), lipase derived from a microorganism belonging to the genus Rhizomucor (eg, Lipase G-100, manufactured by Kyowa Solzyme), lipase derived from a microorganism belonging to the genus Candida (eg, Lipase OF, Meito Sangyo Co., Ltd.) ))
And the like are particularly preferred. From the viewpoint of high optical purity of the product, it is preferable to use a lipase derived from a microorganism belonging to the genus Alcaligenes (eg, Lipase QL, Meito Sangyo Co., Ltd.). These enzymes are commercially available and generally available.

By the above enzyme, 2-acetylthio-
When the enantiomer mixture of 3-phenylpropionate is subjected to asymmetric hydrolysis, the reaction is preferably performed in an aqueous solution, and more preferably in a buffer solution from the viewpoint of the reaction yield and the like. It can also be carried out by appropriately adding an organic solvent.

The use form of the above-mentioned enzyme is not particularly limited, and may be any form such as a purified enzyme, a crude enzyme, and a state contained in cells and tissues. Although these enzymes can be used as they are in the reaction solution, they can also be used by immobilizing them on various carriers. In order to carry out the reaction efficiently, the reaction is preferably carried out under stirring or shaking conditions. The reaction can be carried out in a container having a fixed volume, or can be carried out by continuously replenishing the substrate using, for example, a column or the like on which the above enzyme is immobilized.

The temperature at which the reaction is carried out varies depending on the enzyme used, but is generally preferably from 0 to 60 ° C.
More preferably, it is 10 to 40 ° C.

The pH of the enzyme solution during the reaction varies depending on the enzyme used, but is preferably 2 to 11, and is preferably 5 to 9
Is more preferable.

In the reaction, the ratio of 2-acetylthio-3-phenylpropionic acid ester as the substrate to the enzyme depends on the type of the enzyme used and its purity, but the ratio of enzyme to 1 part by weight of the substrate is 1 part by weight. It is preferably from 0.01 to 100 parts by weight, more preferably from 0.1 to 10 parts by weight.

When the reaction is carried out in an aqueous solution, the concentration of the substrate, 2-acetylthio-3-phenylpropionate, is set at 0.1% with respect to the total amount of the reaction solution in view of the solubility of the substrate and the reaction efficiency. It is preferably from 0.1 to 50% by weight, more preferably from 0.1 to 20% by weight.

Incidentally, these optimum conditions can be determined based on the results of optical purity and absolute configuration measured by optical resolution HPLC analysis described later, with appropriate changes to the conditions.

The 2-acetylthio- formed by the reaction
The method for collecting 2-acetylthio-3-phenylpropionic acid ester that has not reacted with 3-phenylpropionic acid is not particularly limited. For example, the reaction solution may be obtained by adding ethyl acetate,
An unreacted 2-acetylthio-3-phenylpropionate can be recovered by extraction with an organic solvent such as chloroform or ether and using a conventional method such as column chromatography. Of (S) 2-acetylthio-3-phenylpropionic acid, (R) 2-acetylthio-3-phenylpropionic acid or a mixture of these (R) -form and (S) -form by the free acid After that, it can be extracted with an organic solvent such as ethyl acetate. Also, if necessary, by the usual method of resolving optically active chemicals,
By further purifying, optically active 2-acetylthio-3-phenylpropionic acid having high optical purity can be obtained.

[0028]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

Reference Example Preparation of methyl 2-acetylthio-3-phenylpropionate 10.0 g of 2-mercapto-3-phenylpropionic acid
Was dissolved in 50 ml of methanol, and this was slowly added to a cooled solution of 60 ml of acetyl chloride and 450 ml of methanol, and reacted at 65 ° C. for 2 hours. After cooling, the solvent was distilled off under reduced pressure. The residue was dissolved in ethyl acetate, washed with a saturated aqueous solution of sodium hydrogencarbonate and brine, dried over sodium sulfate, and evaporated to remove sodium acetate under reduced pressure.
g of oil was obtained. Then, this is mixed with anhydrous methylene chloride 1
After dissolving in 40 ml, triethylamine (40 ml) and acetic anhydride (22 ml) were added and reacted at room temperature for 1 hour. After washing with 1N hydrochloric acid, a saturated aqueous solution of sodium hydrogencarbonate and saturated saline, and drying over sodium sulfate, methylene chloride is distilled off under reduced pressure, and the residue is purified by a silica gel column (hexane / ethyl acetate = 30: 1). 2.0 g of 2-acetylthio-
3-phenylpropionic acid methyl ester was obtained.

¹ H-NMR (270 MHz, CDCl ₃ )
δ 2.30 (s, 3H), 3.01 (dd, 1H),
3.24 (dd, 1H), 3.65 (s, 3H), 4.
44 (t, 1H), 7.26 (m, 5H) Example 1 5.0 mg of racemic 2-acetylthio-3-phenylpropionic acid methyl ester containing 5.0 mg of various enzymes shown in Table 1 below. Each was added to 1.0 mL of 100 mM potassium phosphate buffer (pH 7.5). The shaking reaction was performed at 30 ° C. for 2 hours. After completion of the reaction, each reaction solution was centrifuged, and unreacted 2-acetylthio-3-phenylpropionic acid methyl ester was extracted with 1.0 mL of ethyl acetate from the supernatant, concentrated, and then subjected to 2-acetylthio-3-phenylpropionic acid. I got

This product was analyzed by optical resolution HPLC (column: Daicel CHIRALCEL OD-H) to determine the absolute configuration together with the optical purity measurement.

Table 1 shows the obtained results.

The reaction yields are calculated on the assumption that the racemic form contains the same amount of the (R) -form and the (S) -form, which are enantiomers of methyl 2-acetylthio-3-phenylpropionate, respectively. The mole percentage (%) of the collected optically active (R) -form or (S) -form 2-acetylthio-3-phenylpropionic acid with respect to the ester.
Expressed as

The optical purity refers to a value represented by the following formula, where R and S represent the proportions of the enantiomer in the R configuration and the enantiomer in the S configuration in the sample, respectively. ee).

[0035]

## EQU1 ## e. e. (%) = (RS / R + S) × 100
(When R ≧ S) or e. e. (%) = (SR−R + S) × 100 (R <S
When)

[0036]

[Table 1] <Results> As shown in Table 1 above, by using various enzymes (such as lipase), it was possible to obtain optically active 2-acetylthio-3-phenylpropionic acid with high optical purity and high reaction yield. . In particular, a lipase derived from a microorganism belonging to the genus Mucor (LIPOZYMEIM, manufactured by Novo), a lipase derived from a microorganism belonging to the genus Rhizomucol (Lipase G-10)
0, manufactured by Kyowa Solzyme), lipase derived from microorganisms belonging to the genus Candida (Lipase OF, Meito Sangyo Co., Ltd.), and when lipase LPBP is used, both the reaction yield (%) and the optical purity (%) It was good. When a lipase derived from a microorganism belonging to the genus Alcaligenes (Lipase QL, Meito Sangyo Co., Ltd.) is used, 2-acetylthio-3 having a high optical purity (%) can be obtained.
-Phenylpropionic acid could be obtained.

[0037]

According to the present invention, optically active 2-acetylthio-3-phenylpropionic acid having high optical purity can be efficiently produced.

Claims (3)

[Claims] [Claim 1] The following general formula (1) or (2) (wherein
R represents an alkyl group having 1 to 10 carbon atoms. ), The enantiomeric mixture of 2-acetylthio-3-phenylpropionic acid ester was converted to the 2-acetylthio-3
Hydrolyzing an ester bond of -phenylpropionic acid ester with an enzyme capable of asymmetric hydrolysis to obtain an optically active 2-acetylthio-3-phenylpropionic acid represented by the following general formula (3) or (4): Optically active 2
A method for producing acetylthio-3-phenylpropionic acid. Embedded image Embedded image Embedded image Embedded image 2. The method according to claim 1, wherein R in the general formulas (1) and (2) is an alkyl group having 1 to 4 carbon atoms. 3. The method according to claim 1, wherein the enzyme is a lipase derived from a microorganism belonging to the genus Mucor, Rhizomucor, Alkalinegens, or Candida.