JP2003125795A - Method for producing optically active 2-acylthio-3- phenylpropionic acids or optically active 2-mercapto-3- phenylpropionic acids - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce optically active 2-acylthio-3-phenylpropionic acid and optically active 2-mercapto-3-phenylpropionic acid of the enantiomer thereof, important as synthetic intermediates of medicines such as a cardio-vascular medicine by using a comparatively inexpensive raw material in high optical purity and high yield by a comparatively short process. SOLUTION: This method comprises the first step for obtaining an enantiomer mixture of acylated mercaptopropionic acids by hydrogenating an acylated mercaptocinnamic acid derivative obtained by using benzaldehydes as starting raw materials and subjecting the raw materials to condensation reaction, and the second step for subjecting the one enantiomer having optical activity in the enantiomer mixture of the acylated mercaptophenylpropionic acids to asymmetric selective hydrolysis by using an enzyme, and isolating the hydrolyzed product.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to optically active 2- (S)-
The present invention relates to a method for producing acylthio-3-phenylpropionic acids. The compound is a useful intermediate for various drugs, and is important as a synthetic intermediate for drugs such as cardiovascular drugs.

[0002]

2. Description of the Related Art Conventional methods for producing 2- (S) -acetylthio-3-phenylpropionic acids are described in JP-A-7-48259, JP-A-11-192097, JP-A-11-196889,
Various methods are known, such as JP-A-10-196254. However, there are problems to be solved in industrial production such as long and complicated steps, the need to use expensive starting materials, and low optical purity or yield of the product. .

[0003]

The object of the present invention is to efficiently produce optically active 2-acylthio-3-phenylpropionic acids having a high optical purity in a small number of steps using inexpensive starting materials. To provide a possible method.

[0004]

Means for Solving the Problems The present inventors have used a simple process in which inexpensive benzaldehydes are used as starting materials, which are condensed to give cinnamic acid derivatives, which are then hydrogenated and asymmetrically hydrolyzed. The inventors have found that optically active 2-acylthio-3-phenylpropionic acid can be produced and have solved the above problems.

That is, the first aspect of the present invention is to hydrogenate an acylated mercaptocinnamic acid represented by the structural formula [1] to obtain an enantiomer mixture of the acylated mercaptophenylpropionic acid represented by the structural formula [2]. Process and
An asymmetric hydrolysis of the (R) or (S) form of the enantiomer mixture of the acylated mercaptophenylpropionic acids with an enzyme to separate a hydrolysis product and an unreacted product. A process for producing an optically active 2-acylthio-3-phenylpropionic acid or its antipode 2-mercapto-3-phenylpropionic acid, which is characterized by comprising steps.

[Chemical 3]

[Chemical 4] (However, the substituent R in the structural formulas [1] and [2] is a hydrogen atom or an alkyl group or an aryl group which may have a substituent, and X represents an acyl group. , There may be more than one.)

Further, an enzyme capable of asymmetrically hydrolyzing a thioester bond is allowed to act on an enantiomeric mixture of 2-acetylthio-3-phenylpropionic acid in which the acyl group X in the structural formula [2] is an acetyl group, Optically active 2- (S) -acetylthio-3-phenylpropionic acid represented by the structural formula [3] and optically active 2- (R) -mercapto-3- represented by the hydrolyzed structural formula [4]. Method for producing phenylpropionic acid, or optically active 2- (R) -acetylthio-3-phenylpropionic acid represented by structural formula [5], and optically active 2 represented by structural formula [6] A method for producing-(S) -mercapto-3-phenylpropionic acid.

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

Further, the method wherein the enzyme for asymmetrically hydrolyzing a thioester bond is esterase, lipase or protease, or the enzyme is Candida (Candida).
ida), Penicillium genus, Rhizopus genus, Mucor genus, Bacillus genus (Bac)
illus), the method wherein the enzyme derived from a microorganism belonging to the genus Pseudomonas is esterase, lipase or protease, and the enzyme is genus Candid.
The method is a lipase, esterase or protease derived from a microorganism belonging to a), Novozym 435 (Novozy
The above method using an immobilized enzyme exemplified by Me. Furthermore, in the above method, the substituent R in the structural formulas [1] and [2] is a hydrogen atom.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention comprises a first step of hydrogenating an acylated mercaptocinnamic acid derivative obtained by a condensation reaction using benzaldehyde as a starting material to obtain an enantiomer mixture of acylated mercaptophenylpropionic acids, and An enantiomeric mixture of acylated mercaptophenylpropionic acids is used to enzymatically hydrolyze one enantiomer of one enantiomer,
It comprises a second step of separating the produced optically active 2-mercapto-3-phenylpropionic acids from the unreacted optically active 2-acylthio-3-phenylpropionic acids.

In the first step of the present invention, an acylated mercaptocinnamic acid represented by the structural formula [1] is used as a starting material. Examples of the acyl group in the structural formula [1] include an acetyl group and a benzoyl group, and an acetyl group is preferable. The acylated mercaptocinnamic acid [1] can be produced at an economically advantageous cost by using an inexpensive benzaldehyde as a starting material.

For the synthesis of the acylated mercaptocinnamic acids, benzaldehyde or substituted benzaldehydes can be used. Specifically, in addition to benzaldehyde, 4-methylbenzaldehyde, 4-ethylbenzaldehyde, 2,4-dimethylbenzaldehyde, 3,5-dimethylbenzaldehyde, 4-isopropylbenzaldehyde, 4-isobutylbenzaldehyde, anisaldehyde, 4-tert- Butylbenzaldehyde, vanillin, 2,4,6
-Trimethylbenzaldehyde, 4-hydroxybenzaldehyde, 4-aminobenzaldehyde, 4-fluorobenzaldehyde, 4-trifluoromethylbenzaldehyde, 2-, or 4-chlorobenzaldehyde.

The above-mentioned benzaldehydes are condensed reaction,
It is converted into cinnamic acids by the so-called Parkin reaction or Parkin-like reaction. Examples of the carbonyl compound used for the condensation include acetic acid, acetic anhydride, chloroacetic acid, thioacetic acid, trifluoroacetic acid, acetylthioacetic acid, rhodanine and the like. In particular, it is an important object of the present invention. 2
To obtain 2-acetylthio-3-phenylcinnamic acid, which is a precursor of-(S) -acetylthio-3-phenylpropionic acid, it is preferable to use benzaldehyde and rhodanine or acetylthioacetic acid. However, the present invention is not limited to these specific examples.

In the first step, the obtained acylated mercaptocinnamic acid [1] is hydrogenated using catalytic hydrogenation or a reducing reagent. For example, Pd-carbon, Ranay-Ni,
Alternatively, catalytic hydrogenation using supported Ru catalyst or Pt catalyst or LiAlH ₄
Double bonds can be easily hydrogenated by carrying out a hydrogenation reaction with a metal hydride such as. The carboxyl group of the acylated mercaptocinnamic acids is subjected to the first step without the need for treatment such as esterification. By the first step, the acetylated mercaptocinnamic acids are hydrogenated to obtain an enantiomeric mixture of acylated mercaptophenylpropionic acids represented by the structural formula [2].

The second step of carrying out the enzymatic reaction, which is a key step of the asymmetric introduction of the present invention, is a mixture of enantiomers of 2-acylthio-3-phenylpropionic acids [2] which is a substrate in a suitable solvent, It is carried out by contacting with an enzyme capable of asymmetrically hydrolyzing the thioester bond of the compound.

A substrate for the enzymatic reaction of the second step of the present invention,
Acylated 2-mercapto-3-phenylpropionic acids
[2] is not limited to an enantiomeric mixture containing the (R) -form and the (S) -form in equal amounts, and may be an enantiomer mixture containing the (R) -form and the (S) -form at an arbitrary ratio.

As the 2-acylthio-3-phenylpropionic acids, not only 2-acylthio-3-phenylpropionic acids but also those having a substituent R on the phenyl group may be used. Examples of the substituent of the phenyl group include, in addition to a hydrogen atom, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl. , Cyclohexyl, cyclohexyloxy, decalyl, norbornyl, bicyclohexyl,
Adamantyl and isomers thereof, phenyl, o-tolyl, m-tolyl, p-tolyl, dimethylphenyl, cumyl,
Mesityl, trimethylphenyl, hydroxyphenyl,
(Substituted) alkyl groups such as hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, etc. ) An aryl group is mentioned. The substituent R is substituted with a functional group such as a hydroxyl group, halogen, nitro group, mercapto group, amino group, amide group, cyano group, carbonyl group, carboxyl group, acetyl group, acyl group, alkoxy group or sulfone group. It may be. Plural substituents R may be present in one phenyl group.

The enzyme used in the second step of the present invention is not particularly limited as long as it has the ability to asymmetrically hydrolyze the thioester bond in the compound [2]. For example, a microorganism collected from nature or an enzyme derived from a microorganism, Commercially available enzymes and the like can be mentioned, and among them, a group of enzymes called esterase, lipase, or protease is preferable.

When a microorganism-derived enzyme is used, examples of suitable microorganisms producing the enzyme include microorganisms such as Candida, Penicillium, Rhizopus, Mucor, Bacillus, and Pseudomonas.
Of these, lipases derived from the genera Candida, Penicillium, Rhizopus, Mucor and Pseudomonas are preferred. As an example containing such a lipase, a lipase derived from the genus Candida "Novozyme 435"
(Manufactured by Novo Nordisk), "Kirazyme L-5" (manufactured by Roche Diagnostics), lipase "Kirazyme L-6" derived from Pseudomonas (manufactured by Roche Diagnostics), or "bioprase". OP-1
There are commercially available enzymes such as "0" (manufactured by Nagase Chemtex),
preferable.

The enzyme may be used in any form such as a purified enzyme, a crude enzyme, or a state in which it is contained in cells or tissues. The enzyme may be used as an inorganic carrier, an organic polymer carrier or the like. It is also effective to use by fixing, and it is effective when repeating the reaction. In particular, "Novozyme 43
It is a preferred embodiment to use the immobilized enzyme exemplified in "5".

In the second step, a batch reaction or a flow-type reaction can be used as the reaction system for asymmetrically hydrolyzing the enantiomeric mixture of 2-acylthio-3-phenylpropionic acid. The asymmetric hydrolysis reaction is preferably performed only in a water solvent or in a two-phase system of an organic solvent and water.

When the asymmetric hydrolysis is carried out in a batch reaction, it is preferably carried out only in a water solvent or in a two-phase system of an organic solvent and water, and it is more preferable to use a buffer solution such as phosphate. The concentration of the enantiomeric mixture of 2-acylthio-3-phenylpropionic acids, which is the substrate, is 0.1 to 50 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 in the range of% by weight, particularly preferably in the range of 0.5 to 20% by weight. The reaction temperature is preferably in the range of 0 to 60 ° C, particularly preferably 20 to 50 ° C, although the suitable range varies depending on the enzyme used. The pH of water or a buffer solvent for the reaction varies depending on the enzyme used, but is preferably in the range of 6 to 10, particularly preferably in the range of 7 to 9.

The batch reaction is preferably carried out with stirring or shaking, but it may be carried out in a stationary state. The amount of the enzyme used is preferably 0.1 to 400% by weight with respect to the substrate 2-acetylthio-3-phenylpropionic acid, but from the viewpoint of reaction efficiency and economy, it is 10 to 10%.
Especially preferred is a range of 0% by weight.

When the asymmetric hydrolysis reaction is carried out in a flow system, the enzyme is packed in a column and intermittently or continuously used.
It can be carried out by supplying a solution of the mixture of -acylthio-3-phenylpropionic acid enantiomers. At that time, a solvent can be newly flowed as a developing solution. The reaction solution can be treated as it is in the next step, and can be returned to the reaction system and circulated until the hydrolysis reaction sufficiently proceeds.

The solvent for the flow-through reaction is preferably an organic solvent or an organic solvent in which water is dissolved. As the organic solvent, for example, ether, methylcyclohexane, t-butyl alcohol, i-propanol, a mixture thereof or the like is preferable. The temperature of the enzyme reaction varies depending on the enzyme used, but is preferably in the range of 0 to 60 ° C, more preferably 20 to 50 ° C. The amount of enzyme, the flow rate of the reaction solution, and the supply rate of the enantiomeric mixture of 2-acetylthio-3-phenylpropionic acid are difficult to unconditionally determine in relation to the required reaction time and the presence or absence of circulation of the reaction solution, and the related conditions Therefore, it is necessary to decide appropriately. As an example, a high conversion rate can be achieved by using an enantiomer concentration in the solvent of 0.1 to 10% by weight, an enzyme to substrate ratio of 5 to 400% by weight, and reacting for 1 to 72 hours. A product having a high optical purity can be obtained.

The optically active 2-mercapto-3-phenylpropionic acid produced by the above batch or distribution method and the unreacted optically active 2-acylthio-3-phenylpropionic acid are separated by various separation means. , Refinement,
It can be collected or acquired. The 2-acylthio-3-phenylpropionic acid that has not been enzymatically hydrolyzed corresponds to the enantiomer acylated product of the 2-mercapto-3-phenylpropionic acids produced by hydrolysis. As the separation means, for example, column chromatography separation, fractional precipitation by pH control, recrystallization, formation of amine salt or mercaptide, or distillation can be used alone or in combination. By this separation and purification means, optically active 2-acylthio-3-phenylpropionic acid having high chemical purity and optical purity can be obtained, or its antipode 2-mercapto-3-phenylpropionic acid can be recovered. Can be done.

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples, but it is a matter of course that the present invention is not limited to the description given in the above embodiments or examples. is there.

Reference Example 1 Preparation of 2-acetylthio-3-phenylpropionic acid 1.27 g (0.012 mol) of benzaldehyde, 1.34 g (0.010 mol) of acetylthioacetic acid, 10 g (0.098 mol) of acetic anhydride and 5.05 g (0.050 mol) of triethylamine were added. Then, the mixture was placed in a flask equipped with a condenser and heated and stirred at 80 ° C. for 7 hours. afterwards,
The reaction solution was cooled to room temperature, poured into water, the precipitate was extracted with ether, and the extract was extracted with 5% aqueous sodium hydroxide solution. Acetylthiocinnamic acid by neutralization with hydrochloric acid and filtration 2.
53 g (yield 95%) was obtained. Next, 0.5% of 5% -Pd carbon powder
Was charged into a 30 ml autoclave and 2.53 g (0.011 mol) of acetylthiocinnamic acid obtained was added to isopropyl alcohol (1
0.0 g) solution was added. Hydrogen up to 10kgf / cm2, 100 ℃
And reacted for 3 hours. The product liquid was filtered to remove the catalyst, and the product was analyzed by liquid chromatography. The yield of 2-mercapto-3-phenylpropionic acid was 70% (1.45 g). Subsequently, the solvent was distilled off and the residue was dissolved in a 20% KOH aqueous solution. The mixture was further cooled on ice, 4.07 g (0.040 mol) of acetic anhydride was added dropwise, and the mixture was stirred at room temperature for 30 minutes. Then, it was neutralized with 5M hydrochloric acid, extracted with ether, and the solvent was evaporated under reduced pressure. When the obtained oily substance was cooled, an enantiomeric mixture consisting of racemic 2-acetylthio-3-phenylpropionic acid was obtained as crystals (1.61 g, 90%).

Example 1 Preparation of optically active 2-acetylthio-3-phenylpropionic acid and its antipode 2-mercapto-3-phenylpropionic acid 2-acetylthio-3-phenylpropionic acid racemate (10 mg) Potassium phosphate buffer (KH2PO4 / NaOH, Ph7.
5) Dissolved in 2 ml, 10 mg of each enzyme shown in Table 1 was added thereto, and the mixture was tightly capped and allowed to react for 15 hours in a shaking culture machine at 30 ° C. After completion of the reaction, the enzyme was removed by filtration, and unreacted 2-acetylthio-3-phenylpropionic acid and the reaction product 2-mercapto-3-phenylpropionic acid were extracted with ethyl acetate. Anhydrous sodium sulfate was added to the organic layer for dehydration, the solvent was distilled off under reduced pressure, and unreacted 2-acetylthio-3-phenylpropionic acid (APP) and its antipode 2-mercapto-3-phenylpropionic acid ( MPP) was obtained as a mixture of enantiomers. Optical resolution column (Daicel Corporation)
The optical purity was measured using a commercial product, CHIRALCEL OD-H), and the results shown in Table 1 were obtained. In the table, "-
"-" Indicates that the measurement was not performed.

[0028]

[Table 1]

Example 2 A racemate of 2-acetylthio-3-phenylpropionic acid (42 mg) was dissolved in 1 ml of ether, and 3 ml of cyclohexane and 6 ml of ion-exchanged water were added to the mixture, and a lipase (Novonor) from Candida was added as an enzyme. Disco, product name Novozyme 435) (42 mg) was added and the mixture was kept at 40 ° C for 4 hours.
Shake for 0 hours. After the reaction was completed, the enzyme was filtered off to remove unreacted 2- (R) -acetylthio-3-phenylpropionic acid and the reaction product 2- (S) -mercapto-3-phenylpropionic acid with diethyl ether. Extracted using.
Anhydrous sodium sulfate was added to the organic layer for dehydration, and the solvent was distilled off under reduced pressure to obtain optically active 2- (R) -acetylthio-3-phenylpropionic acid and 2- (S) -mercapto-3-phenylpropionic acid. To obtain a mixture of enantiomers. Optical resolution column (manufactured by Daicel Corp., trade name CHIRALCEL OD-
H) was used to measure the optical purity, and the optical purity of 2- (R) -acetylthio-3-phenylpropionic acid was found to be 9
It was 6.6% ee (yield 18 mg, yield 85.7%). Again 2
The optical purity of-(S) -mercapto-3-phenylpropionic acid was 73.3% ee.

Example 3 A racemate of 2-acetylthio-3-phenylpropionic acid (0.2 g) obtained in the same manner as in Example 1 was dissolved in 0.5 ml of dibutyl ether, and cyclohexane (4.5 m
l), ion-exchanged water (5 ml) was added, and Novozyme 435
(0.8 g) was added, and the mixture was shaken at 40 ° C. for 40 hours. After completion of the reaction, the enzyme is removed by filtration to remove unreacted 2- (R) -acetylthio-3-phenylpropionic acid and the reaction product 2-
Mercapto-3-phenylpropionic acid was extracted with diethyl ether. Anhydrous sodium sulfate was added to the organic layer for dehydration, and the solvent was distilled off under reduced pressure to obtain optically active 2- (R) -acetylthio-3-phenylpropionic acid and enantiomers of 2-mercapto-3-phenylpropionic acid. A mixture was obtained. The optical purities of 2- (R) -acetylthio-3-phenylpropionic acid and 2- (S) -mercapto-3-phenylpropionic acid are 93.6% ee and 22.4%, respectively.
It was ee.

Example 4 A glass column packed with Novozyme 435 (inner diameter 1 cm,
(10 cm in length) was immersed in a constant temperature bath and kept at 40 ° C. Then, a solution of 2-acetylthio-3-phenylpropionic acid racemate (0.2 g), dibutyl ether (0.5 ml) and cyclohexane (9.5 ml) obtained in the same manner as in Example 1 was passed through water (5 ml). Was fed at a rate of 0.1 ml / min for 9 hours. After that, 2-propanol (50vol%), dibutyl ether (50
vol%) of the solvent, and the reaction solution in the column is allowed to flow out to obtain an enantiomer mixture of optically active 2- (R) -acetylthio-3-phenylpropionic acid and 2- (S) -mercapto-3-phenylpropionic acid. Got Analysis of the reaction solution revealed that the optical purity of 2- (R) -acetylthio-3-phenylpropionic acid was 91% ee (0.45 g, yield 90%), 2-
The optical purity of (S) -mercapto-3-phenylpropionic acid was 75% ee (0.37 g, yield 92%).

[0032]

According to the present invention, an optically active 2-acylthio-3-phenylpropionic acid or an optically active 2-mercapto-3-phenylpropionic acid derived from its antipode is
With a high optical purity and a high yield, a relatively inexpensive raw material can be used to industrially manufacture in a relatively short process.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhiro Yamada             22 Wadai, Tsukuba City, Ibaraki Mitsubishi Gas Chemical             Research Institute, Inc. (72) Inventor Shoko Koshiishi             22 Wadai, Tsukuba City, Ibaraki Mitsubishi Gas Chemical             Research Institute, Inc. F-term (reference) 4B064 AD21 CA31 CB01 CD27 DA16

Claims (7)

[Claims] 1. A first step of hydrogenating an acylated mercaptocinnamic acid represented by the structural formula [1] to obtain an enantiomer mixture of acylated mercaptophenylpropionic acids represented by the structural formula [2], and An optically active 2-mercapto-produced product obtained by asymmetrically selectively hydrolyzing the enantiomer mixture of the acylated mercaptophenylpropionic acids with one of the enantiomers using an enzyme.
Of optically active 2-acylthio-3-phenylpropionic acids or optically active 2-mercapto-3-phenylpropionic acids, which comprises a second step of separating 3-phenylpropionic acids from the unreacted enantiomer. Production method. [Chemical 1] [Chemical 2] (However, the substituent R in the structural formulas [1] and [2] is a hydrogen atom, or an alkyl group or an aryl group which may have a substituent, and X represents an acyl group.
There may be a plurality of substituents R. ) 2. The method according to claim 1, wherein the acyl group X in the structural formulas [1] and [2] is an acetyl group. 3. The enzyme used in the second step is esterase,
The method according to claim 1, which is a lipase or a protease. 4. The enzyme used in the second step is Candida (Ca
ndida), Penicillium genus, Rhizopus genus, Mucor genus, Bacillus genus (Bac)
illus), an enzyme derived from a microorganism belonging to the genus Pseudomonas. 5. The method according to claim 4, wherein the enzyme is a lipase, esterase or protease derived from a microorganism belonging to the genus Candida. 6. The method according to claim 1, wherein the enzyme is an immobilized enzyme. 7. The method according to claim 1, wherein the substituent R in the structural formulas [1] and [2] is a hydrogen atom.