JPH0242476B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing optically active β-(S)-aminoglutaric acid monoalkyl ester. In physiologically active substances having an asymmetric carbon, only one optically active form often exhibits physiological activity, and its enantiomer is often inactive. Representative examples include β-lactam compounds such as penicillin, cephalosporin, and thienamycin. For example, thienamycin has the following formula: It is a compound that has a carbapenam nucleus with the three-dimensional structure of L-aspartic acid. The following formula is derived in multiple steps from the dialkyl ester of It can be totally synthesized via (S)-4-alkoxycarbonylmethylazetidin-2-one [wherein R ₁ is an alkyl group] (see JP-A-55-27169). The present inventor believes that if optically active β-(S)-aminoglutarate monoalkyl ester can be created, it can be used as an intermediate for producing the azetidinone derivative having the above-mentioned S-configuration useful for thienamycin synthesis. Therefore, they predicted that it would be useful as an important synthetic intermediate for carbapenems. Based on this foresight, the present inventor conducted research and discovered that optically inactive benzyloxycarbonylaminoglutarate dimethyl ester, which can be easily obtained by organic synthesis, was synthesized using an ester hydrolase derived from animal liver.
It was discovered that when treated with , only one ester group is eliminated by hydrolysis, producing an optically active monomethyl ester. It was also found that optically active β-(S)-aminoglutaric acid monomethyl ester was obtained when the benzyloxycarbonyl group as an amino protecting group was removed by a conventional method. however

[Formula] Me = methyl In the above reaction, methoxycarbonylmethyl, which is in an enantiotopic relationship with β-benzyloxycarbonylaminoglutarate dimethyl ester (), which is a compound belonging to the Cs point group with a plane of symmetry, is Only one of the groups is selectively hydrolyzed by the enzyme, and the terminal methyl (Me) is eliminated, yielding optically active β-(S)-benzyloxycarbonylaminoglutarate monomethyl ester (), which is then deprotected. It produces optically active β-(S)-aminoglutaric acid monomethyl ester (). The above reaction is characterized by a prochiral starting material ()
The point is to obtain a chiral object () from a chiral intermediate (). Conventionally, research in this field has been limited to enzymatic chemical research, and has been far from the goal of synthetically producing useful substances such as antibiotics. i.e. Cohen and Kedo Ory (SG
Cohen, E.Khedouri, Nature, 186, 75 (1960))
As part of their enzymatic chemistry research, they obtained optically active β-(R)-acetamidoglutarate monoester from β-acetamidoglutarate diethyl ester using α-chymotrypsin, a type of Swiss protease. However, since the amino group of this starting material is acetylated, it is quite difficult to convert the acetylamino group into a free amino group without hydrolyzing the ester group of the product. In the case of ethyl ester groups, the rate of enzymatic decomposition is slow, requiring a large amount of α-chymotrypsin or a long time; therefore, even if organic synthesis methods are skillfully combined, it is difficult to convert them into physiologically active substances. It was considered difficult. Furthermore, the steric configuration is assigned to R, and cannot be applied to the production of biologically active β-lactams. Although the present inventors used 3-aminoglutarate dialkyl ester as a substrate, which was recognized to have such disadvantages, the present inventors carefully considered the type of protecting group for the amino group and the enzyme system used to select it. As a result, the present invention was achieved by discovering that β-aminoglutaric acid monoalkyl ester having an optically active (S) configuration can be produced from the above-mentioned substrate compound. The present invention is based on the following formula [In the formula, R is an alkyl group having 1 to 4 carbon atoms, and A
is an amino-protecting group that can be removed by catalytic reduction or mild hydrolysis] is treated with an ester hydrolase derived from animal liver to selectively remove one of the ester groups (R ), then the amino protecting group (A)
The following equation is characterized by the usual elimination of The gist of the present invention is a method for producing an optically active β-(S)-aminoglutaric acid monoalkyl ester, [wherein R has the same meaning as above]. The amino protecting group (A) in the β-protected aminoglutarate dialkyl ester (i) used as a starting compound in the method of the present invention can be removed by catalytic reduction, and can be removed by benzyl, benzhydryl, and benzyloxycarbonyl groups. An aralkyloxycarbonyl group such as the above is preferred, but a t-butoxycarbonyl group or the like which can be eliminated by mild hydrolysis may also be used. This protecting group can be introduced by a known amino protection method for peptide synthesis. Further, the alkyl group (R) for forming an ester can be a lower alkyl group such as a methyl group or an ethyl group. As the ester hydrolase (esterase), esterases derived from various animal livers can be used, but pig liver esterase is preferred as it is the easiest to obtain. The enzyme reaction in the method of the present invention is conveniently carried out by dissolving the β-protected aminoglutarate dialkyl ester (i) in a phosphate buffer, adding an ester hydrolase, and allowing the reaction to proceed under stirring. It is. Water is usually used as the reaction solution, but
If necessary, an organic solvent such as dimethylformamide, acetone, or lower alkanol can be used at a concentration of 10% or less or at a concentration that does not impair enzyme activity. The pH of the reaction solution is 7.0 to 9.0, preferably 7.0 to
It is 8.0. The reaction temperature may be any temperature as long as the activity of the enzyme is maintained, and 20 to 30°C is usually preferably used. The reaction time may be 1 to 2 hours, depending on the reaction volume and the amount of enzyme. The amount of enzyme may be a catalytic amount, but in consideration of the reaction rate, the amount of protein used is preferably 0.001 to 1% by weight based on the substrate compound (i). After the reaction, adjust the pH to 7.0 or less with dilute hydrochloric acid and store at 20℃.
Dry to a concentration below. The product is extracted with methanol and concentrated to obtain the crude product. When this is separated and purified using a cellulose column, β-(S)-protected aminoglutaric acid monoester is obtained in high yield. Then, the amino group is removed and protected by a known method such as catalytic reduction to obtain the product β-(S)-aminoglutaric acid monoalkyl ester (ii). Its optical purity varied depending on the reaction conditions, but it showed negative [α] _D , and its absolute structure was determined to be derived from a β-lactam compound and identified as a separately synthesized substance. Therefore, in the present invention, the middle proton of the two enantiotopic alkoxycarbonylmethyl groups of the substrate compound (i) is
This means that the alkyl group was preferentially hydrolyzed. Moreover, surprisingly, a product with a different steric configuration was obtained when the amino group of substrate compound (i) was a free amino group or an acetylamino group. The β-(S)-aminoglutarate monomethyl ester and monoethyl ester obtained in the present invention exhibit antibacterial activity against Gram-positive bacteria, especially Staphylococcus,
Useful as an antibacterial agent. Furthermore, the optically active -(S)-aminoglutaric acid monoalkyl ester obtained in the present invention can be converted into an important intermediate (S)- of carbapenel β-lactam in one step by an organic synthetic method.
4-Alkoxycarbonylmethylazetidine-2
- It can be easily turned on. Therefore, the method of the present invention is generally applied as a method for producing an optically active free β-amino acid by an enzymatic chemical method, and the optically active amino acid as a product has a free amino group. When a carboxylic acid or ester group is subjected to an appropriate chemical conversion, the substituent group can be arbitrarily converted depending on the asymmetric carbon of the physiologically active substance, which is highly useful. Hereinafter, the present invention will be explained with reference to examples. Example 1 (a) Dissolve 465 mg (1.5 mmol) of β-benzyloxycarbonylaminoglutarate dimethyl ester in 1.5 ml of acetone and add it to PH8.70 phosphate buffer.
Add 45ml. Esterase obtained from pig liver (Sigma, E-3128) as protein amount
Add 2.7 mg and leave at 25°C for 6 hours with occasional stirring. Add 2.5 ml of 2N hydrochloric acid to adjust the pH of the solution to approximately 1, and extract with methylene chloride. After temporary drying with anhydrous sodium sulfate and concentration, crude crystals 419
Get mg. When purified by silica gel column chromatography, [α] ²⁵ _D +0.69° (c7.45, CHCl ₃ )
Optically active β-(S)-benzyloxycarbonylaminoglutarate monomethyl ester of 410
mg (93% yield) was obtained. mp97.0−97.5℃. I (KBr); 3330, 2840-2960, 1740, 1725,
1700 cm ^-1 H-NMR (CDCl ₃ ); δ2.69 (bd, 4H, CH ₂ J=
6Hz), δ3.65 (S, 3H, Co ₂ Me), δ4.17~
4.53 (m, 1H, CH), δ5.07 (s, 2H, OC),
δ5.63 (bd, 1H, NH), δ7.30 (s, 5H, Ph) Elemental analysis value Calculated value (C ₁₄ H ₁₇ O ₆ N):
C, 56.94; H, 5.80;, 4.74. Actual values: C, 57.05; H, 5.84; N, 4.69. (b) 385 mg of monomethyl ester obtained as above.
(1.3 mmol) in 20 ml of methanol 10
Add 40 mg of % palladium on carbon and add 30% palladium on carbon under hydrogen atmosphere.
Stir for a minute. When the reaction solution is filtered and concentrated, β
- Obtain 205 mg of an oily product of (S) aminoglutarate monomethyl ester (yield 98%). This one shows [α] ²⁵ _D −5.52° (c3.26, H ₂ O). The IR, NMR, and elemental analysis values are as follows. IR: 3440, 1730, 2400 ~ 2900 cm ^{- 1} H-NMR (D ₂ O): δ2.59 (bd 2H, J = 6
Hz), δ2.84 (bd 2H, J=6Hz) δ3.76 (s,
3H), δ3.85-4.05 (m, 1H). Elemental analysis value: Calculated value (C ₆ H ₁₁ O ₄ N);
C44.71; H, 6.88; N, 8.69 Actual value: C, 44.73; H, 6.87; N8.65. Example 2 Enzyme treatment was performed in the same manner as in Example 1 using 500 mg of β-benzhydrylaminoglutarate diethyl ester, followed by catalytic reduction on palladium carbon.
β-(S)-aminoglutaric monoester oil
Got 400mg. IR: 3445, 1728cm ^- .

Claims (1)

[Claims] Linear formula [In the formula, R is an alkyl group having 1 to 4 carbon atoms, and A
is an amino-protecting group that can be removed by catalytic reduction or mild hydrolysis] is treated with an animal liver-derived ester hydrolase to selectively remove one of the ester groups (R ), then the amino protecting group (A)
The following equation is characterized by the usual elimination of A method for producing an optically active β-(S)-aminoglutaric acid monoalkyl ester, [wherein R has the same meaning as above].