JPS6265688A - Stereoselective hydrolysis of cyanohydrin derivative - Google Patents

Abstract

PURPOSE:To obtain an optically active cyanohydrin compound and cyanohydrin ester, easily, by reacting a specific cyanohydrin derivative with an esterase under neutral or acidic condition and subjecting the reaction product to asymmetric hydrolysis. CONSTITUTION:The optically active cyanohydrin compound of formula II and an optically active cyanohydrin ester of formula II which is an antipode ester of the compound of formula II can be produced by (1) reacting (A) the cyanohydrin derivative of formula I [R1 is H, 1-18C alkyl, 2-18C alkenyl, etc.; R2 is 1-18C alkyl, aryl(substituted) 2-18C alkenyl, etc.) with (B) an esterase capable of asymmetrically hydrolyzing the cyanohydrin derivative and originated from microorganism belonging to Arthrobacter genus, Alcaligenes genus, etc., at <=7pH and (2) carrying out the asymmetric hydrolysis of the reaction product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stereoselective hydrolysis of cyanohydrin derivatives. For more details, refer to the general formula +11 [wherein R is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an alkynyl group having 2 to 18 carbon atoms, or a halogen having 1 to 4 carbon atoms. substituted alkyl group,
Halogen-substituted alkenyl group having 2 to 4 carbon atoms, 2 to 4 carbon atoms
4 represents a halogen-substituted alkynyl group or an alkoxyl group having 1 to 8 carbon atoms, and R2 represents an alkyl group having 1 to 18 carbon atoms, or an alkenyl group having 2 to 18 carbon atoms which may be substituted with an aryl group. or represents an alkynyl group having 2 to 18 carbon atoms. ] A cyanohydrin derivative represented by the above is asymmetrically hydrolyzed to produce an optically active cyanohydrin represented by the general formula (nl [wherein R2 has the same meaning as above, and * represents an asymmetric carbon]) An ester of a compound and its enantiomer of the general formula (I[[) [wherein R, R
2 and * have the same meanings as above. ] This invention relates to a method for stereoselective hydrolysis of a cyanohydrin derivative by obtaining an optically active cyanohydrin ester represented by the following.

Optically active cyanohydrins and their esters represented by general formulas (n) and (II[) are, for example, Cerebroside (G, Kawaii
Biochem, Biophys, Acta, 7
54, 248 (1988)), it is an extremely useful compound because it can be easily derived into optically active α-hydroxycarboxylic acid esters, which are important as intermediates for the synthesis of various physiologically active compounds.

As a result of various studies on the production method of these optically active compounds, the present inventors have found that the above-mentioned general formula +I) can be produced by biochemically asymmetrically hydrolyzing the cyanohydrin derivative represented by the above-mentioned general formula +I) as a raw material. It was discovered that an optically active cyanohydrin compound represented by the formula (OI) and an optically active cyanohydrin ester represented by the general formula (III) can be obtained, and the present invention was accomplished based on this discovery.

That is, the present invention provides a cyanohydrin derivative represented by general formula (11) with Arthrobacter (Ar), which has the ability to act on the cyanohydrin derivative and asymmetrically hydrolyze it.
throbacter ) genus, 7/lz calligene x (
Alcaligenes), Achromobacter (
An esterase derived from a microorganism belonging to the genus Achromobacter, Pseudomonas, or Chromobacterium is reacted at pH 7 or below, and asymmetrically hydrolyzed to produce an optically active cyanohydrin compound represented by the general formula (Ill). The present invention relates to a method for stereoselective hydrolysis of cyanohydrin derivatives, which is characterized by obtaining an optically active cyanohydrin ester represented by the general formula (1), which is an ester of its enantiomer.

[ In the formula, R2 and * represent the same meanings as above, and R3
can be converted into an optically active α-hydroxycarboxylic acid ester represented by an alkyl group, haloalkyl group or alkoxyalkyl group having 1 to 8 carbon atoms.

The method of the present invention will be explained below.

In the present invention, esterase refers to esterase in a broad sense including lipase, and specific examples of microorganisms belonging to the genus ldl that produce the esterase used in the present invention include the following bacterial cells. It will be done.

(11 Arthrobacter, Simbrex IFO-
8580Arthrobacter simplex
(2) Alcaligenes faecalis IFO-1
2669Alcaligenes faecalis
(3) Achromobacter ATCC-219
ATCC-21910Achro Sp.

141 Pseudomonas fluorescens I
FO-8081Pseudomonas fluo
rescens (5) Chromobacterium viscosum ATCC-6918ATCC-6918Ch
ro um viscosum These strains are all available from Osaka Clono Foundation Institute for Fermentation (IFO) or Ame.
rican TypeCulture Co11ect
ion (ATCC) and can be obtained from this institution.

Furthermore, some esterases derived from microorganisms are commercially available, and these commercially available enzymes can also be used for the purpose of the present invention.

Commercially available enzymes that can be used in the present invention include those shown below.

In carrying out the present invention, in the cyanohydrin derivative represented by the general formula (Il) used as a raw material,
The content of the optical isomer is not particularly limited, but for the purpose of the present invention, it generally contains approximately equal amounts of (R1 monomer and (8) monomer) obtained by ordinary chemical synthesis methods. The so-called racemate is used.

In addition, the asymmetric hydrolysis reaction is performed using a culture solution containing the above-mentioned microorganisms, a culture liquid, an aqueous suspension of bacterial cells, or a treatment product thereof, such as a crude esterase or a purified esterase, and a cyanohydrin derivative as the raw material. This is done by mixing, stirring or shaking. If necessary, a non-ester surfactant may be added.

It is also possible to immobilize the enzyme and use it.

At this time, the reaction temperature is suitably 10 to 65°C, particularly preferably 20 to 50°C. The reaction time is usually 8 to 48 hours, but the reaction temperature may be increased or
The reaction time can also be shortened by using a highly active enzyme.

It is important that the reaction pH is below pH 7, and pH 8.5 is essential.
It is preferable to maintain the pH within the range of 6.0 to 6.0.

Furthermore, in order to prevent the pH from decreasing due to organic acids such as acetic acid generated by hydrolysis, a buffer solution is used to adjust the pH.
It is desirable to control the As the buffer solution, either an inorganic acid salt buffer or an organic acid salt buffer can be used.

The concentration of the cyasohydrin derivative represented by the general formula fI), which is the substrate, is approximately
%, preferably 5 to 40 W/W%.

After performing the asymmetric hydrolysis reaction in this way, the optically active cyanohydrin compound represented by the general formula That is, the optically active cyanohydrin ester represented by the general formula (1) is separated and recovered.

As a specific example of such a separation and recovery operation, for example, the reaction completed liquid is extracted with an organic solvent such as ether, ethyl acetate, or toluene, this extract is subjected to column chromatography using silica gel, etc., and hexane-acetic acid is extracted. By elution with an ethyl mixed solution, the free general formula (I
The optically active cyanohydrin compound represented by I) and the unreacted ester of the enantiomer can be separated and obtained.

In the cyasohydrin derivative represented by the general formula (Il) which is the raw material compound of the method of the present invention, the carboxylic acid component thereof is, for example, formic acid, acetic acid, propionic acid, butyric acid.
Examples include 73 grass acid, 1 μ grass acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, or their halogen-substituted products, and ease of handling. A fatty acid having 2 to 12 carbon atoms or a halogen-substituted fatty acid having 1 to 4 carbon atoms having one chlorine atom or bromine atom at the α-position is preferred, and moreover, from the viewpoint of ease of availability and economical considerations. From these, acetic acid, propionic acid, monochloroacetic acid, and monobromoacetic acid are more preferred.

Specific examples of the substituent R2 include methyl group, ethyl group, n-propyl group, n-butyl group, 2-methyl 10-pyl group, n-hexyl group, n-heptyl group, n-octyl group, n- Alkyl groups such as nonyl M, n-decyl group, n-undecyl group, ■-butenyl group, 1-methyl-1-butenyl group, alkenyl group such as 2-propenyl group, phenoxyphenylvinyl group, chlorophenylvinyl group, bromo Examples include substituted phenylalkenyl groups such as a phenylvinyl group, fluorophenylvinyl group, methylphenylvinyl group, and ethylphenylvinyl group, and alkynyl groups such as a propargyl group, 1-propynyl group, 1-butynyl group, and ethynyl group.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Examples 1 to 5] Acetate ester 600'9 of the (R,S) type cyanohydrin compound listed in Table 1 below and esterase originating from the genus Pseudomonas ("Amano" P) 15I19 were mixed in acetate buffer (1) H5, 0) and reacted with stirring at 80°C. After reacting for 15 hours, the reaction product was extracted with ethyl acetate. The extract was subjected to silica gel column chromatography to obtain an optically active cyanohydrin compound and its enantiomer acetate ester.

A part of the optically active 2-hydroxy ester thus obtained was taken and (S)-tfJ-α-trifluoromethyl-
After reacting with α-methoxyphenylacetic acid chloride, it was analyzed by high performance liquid chromatography to measure the optical isomer ratio.

The results are shown in Table 1.

Claims (1)

[Claims] 1) General formula (I) ▲There are numerical formulas, chemical formulas, tables, etc.▼(I) [In the formula, R_1 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a C 2 to 18 alkyl group. Alkenyl group, alkynyl group having 2 to 18 carbon atoms, halogen-substituted alkyl group having 1 to 4 carbon atoms, halogen-substituted alkenyl group having 2 to 4 carbon atoms, halogen-substituted alkynyl group having 2 to 4 carbon atoms, or halogen-substituted alkynyl group having 1 to 8 carbon atoms represents an alkoxyl group having 1 to 18 carbon atoms, R_2 represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms which may be substituted with an aryl group, or an alkynyl group having 2 to 18 carbon atoms. represent. ] A microorganism derived from the genus Arthrobacter, the genus Alcaligenes, the genus Achromobacter, the genus Pseudomonas, or the genus Chromobacterium, which has the ability to asymmetrically hydrolyze the cyanohydrin derivative by acting on the cyanohydrin derivative represented by Esterase is reacted at pH 7 or below and asymmetrically hydrolyzed, resulting in optically active general formula (II) ▲Mathematical formulas, chemical formulas, tables, etc.▼(II) [In the formula, R_2 has the same meaning as above. , * represents an asymmetric carbon. [In the formula, R_1, R_2 and * have the same meanings as above. has. ] A method for stereoselective hydrolysis of a cyanohydrin derivative, characterized by obtaining an optically active cyanohydrin ester represented by: (2) In the ester represented by the above general formula (I), the substituent R_1 is a methyl group, an ethyl group, a monochloromethyl group, a monobromomethyl group, a methoxy group, an ethoxy group, or a propoxy group, Claim 1 The method described in section. (3) The method according to claim 1 or 2, wherein the asymmetric hydrolysis reaction is carried out at a pH in the range of 3.5 to 6.0. (4) The method according to claim 1, 2 or 3, wherein the asymmetric hydrolysis reaction is carried out at 20 to 50°C.