JPS6234035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing (2R·4R)-4-alkyl-2-piperidinecarboxylic acid or its L-tartrate salt. More specifically, (2R・4R)-1-(N ²
-arylsulfonyl-L-arginyl)-4-
The present invention relates to a method for producing (2R·4R)-4-alkyl-2-piperidinecarboxylic acid, which is an intermediate of alkyl-2-piperidinecarboxylic acid, or its L-tartrate salt.

Regarding 4-alkyl-2-piperidinecarboxylic acid, which is useful as an intermediate for N ² -arylsulfonyl-L-arginine amides having anticoagulant properties, a patent application was filed in 1983-150064, but later it was investigated. Results 4-Alkyl-2-piperidinecarboxylic acid contains four types of optical isomers, and one of them, (2R・4R)-4-alkyl-2-piperidinecarboxylic acid, has anticoagulant effect. It was found that this is an important main factor that promotes the expression of remarkable pharmacological effects.

Although a method for resolving the four types of optical isomers is not yet known, as a result of examining various resolution methods, we found that the use of L-tartaric acid provides particularly remarkable effectiveness (2R・4R)-4 The inventors have discovered that -alkyl-2-piperidinecarboxylic acid can be isolated in high yield and have arrived at the present invention.

That is, the present invention obtains (2R·4R)-4-alkyl-2-piperidinecarboxylic acid salt by contacting 4-alkyl-2-piperidinecarboxylic acid with L-tartaric acid in water or an aqueous solvent, and optionally (2R・4R)-4-alkyl-2, characterized in that L-tartaric acid is desorbed and removed from the L-tartrate salt.
- A method for producing piperidine carboxylic acid or its L-tartrate salt.

The present invention will be explained in detail below.

The alkyl group of the 4-alkyl-2-piperidinecarboxylic acid of the present invention is a _C1 to _C5 group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, etc.
A lower alkyl group is preferred.

4-alkyl-2-piperidinecarboxylic acid has trans and cis forms, each of which has two types of optical isomers.

Compounds that exhibit remarkable pharmacological activity when made into ^N2 -arylsulfonyl-L-argininamides, which are the ultimate anticoagulants, belong to the trans isomer.
Among them, (2R・4R)-4-alkyl-2-piperidinecarboxylic acid obtained in the present invention is significantly superior to the other optical isomer (2S・4S)-4-alkyl-2-piperidinecarboxylic acid. Shows pharmacological activity.

In the present invention, highly purified (2R・4R)-4-alkyl-2 is obtained from 4-alkyl-2-piperidinecarboxylic acid in which the trans isomer and the cis isomer are mixed in any ratio, or from the trans isomer separated in advance. - piperidine carboxylic acid can be obtained.

Therefore, the 4-alkyl-2-piperidinecarboxylic acid used as a raw material in the present invention includes those in which the trans form and the cis form are mixed in any proportion, and even those containing only the trans form.

The method for producing (2R·4R)-4-alkyl-2-piperidinecarboxylic acid will be described below.

4-alkyl-2-piperidinecarboxylic acid and L
- Mixing with tartaric acid in water or an aqueous solvent.
The aqueous solvent is a mixed solvent of water and a hydrophilic solvent such as lower alcohols such as methanol, ethanol, and propanol, ethers such as tetrahydrofuran and dioxane, and acetone. The mixing ratio is preferably 3 to 500 times the weight of the hydrophilic solvent to water. Alternatively, 4-alkyl-2-piperidinecarboxylic acid and L-tartaric acid may be first added and dissolved in water, and then a hydrophilic solvent may be added.

4-alkyl-2-piperidinecarboxylic acid and L
-The amount of tartaric acid used is L per mol of carboxylic acid.
- 1.5 to 0.7 mol of tartaric acid are used, preferably equimolar. Further, the amount of 4-alkyl-2-piperidinecarboxylic acid is preferably in the range of 1 to 30% by weight based on the solvent.

4-alkyl-2-piperidinecarboxylic acid and L
- Tartaric acid may be added in either order, or both may be dissolved in separate solvents and then mixed.

The reaction temperature is preferably a temperature at which both are uniformly dissolved, and is not particularly limited, but preferably from room temperature to the boiling point of the solvent.

Further, a hydrophilic solvent may be added as necessary.

According to this method, almost 100% of the crystals obtained are a 1:1 salt of (2R・4R)-4-alkyl-2-piperidinecarboxylic acid and L-tartaric acid, and other optical isomers of L-tartaric acid Salt does not crystallize. Therefore, highly pure L-tartrate can be obtained simply by taking the obtained crystals and washing the attached mother liquor. If necessary, it can be recrystallized from a water-alcohol, preferably a water-ethanol solvent.

The above-mentioned method can be applied even when 4-alkyl-2-piperidinecarboxylic acid is a mixture of the trans form and the cis form in any proportion, or when the 4-alkyl-2-piperidine carboxylic acid is only the trans form. When using the trans isomer as a starting material, 4-alkyl-2-piperidinecarboxylic acid is esterified with a lower alcohol, the cis isomer and the trans isomer are separated by distillation to obtain the trans isomer, and this is hydrolyzed to form the trans isomer. 4-alkyl-2-piperidic acid can be obtained.

If necessary, L-tartaric acid is desorbed and removed from the obtained L-tartrate salt of (2R・4R)-4-alkyl-2-piperidinecarboxylic acid to form (2R・4R)-4-alkyl-2-piperidine. Carboxylic acids can be obtained. When synthesizing the final anticoagulant,
L-tartrate may be used as is for the next reaction, but
It is preferable to remove L-tartaric acid in advance.

The desorption method may be a conventional method, and L-tartaric acid is preferably removed according to a conventional method using a strongly acidic ion exchange resin. Alternatively, L-tartrate can be directly esterified and separated into (2R·4R)4-alkyl-2-piperidinecarboxylic acid ester and L-tartrate by distillation.

The (2R·4R)-4-alkyl-2-piperidinecarboxylic acid or its L-tartrate obtained by the above method serves as an intermediate for ^N2 -arylsulfonyl-L-arginine amides. Among N ² -arylsulfonyl-L-argininamides, it has a particularly effective anticoagulant effect (2R・4R)-1-
The synthetic route will be explained by taking [ ^N2- (3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid as an example.

R is C ₁ such as methyl group, ethyl group, propyl group, etc.
~ _C5 lower alkyl group. * in the formula represents an asymmetric carbon atom. Compound () is obtained by condensing N2 ^- Boc-nitro-L-arginine () and (2R·4R)4-methyl-2-piperidinecarboxylic acid ester () in a mixed acid state using isobutyl chloroformate. When treated under a strong acid such as anhydrous hydrochloric acid-ethyl acetate, the Boc group is acid-decomposed and eliminated to form the compound (). When () is condensed with 3-methylquinoline-8-sulfonyl chloride in the presence of a base, compound () is obtained. When () is hydrolyzed in an aqueous NaOH solution and then reduced in a hydrogen atmosphere using a Pd-C catalyst, the nitro group and pyridine ring, which are the protective groups of the guanidino group, are hydrogenated, resulting in a final product with a strong anticoagulant effect. It is possible to obtain substances.

(2R・4R)−1− obtained as above
[ ^N2- (3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid is 4-methyl-2-piperidinecarboxylic acid. is the other optical isomer of the trans isomer (2S・
(2S・4S)-1-[N ² -(3
-Methyl-1,2,3,4-tetrahydro-8-
The anticoagulant effect is approximately 3500 times more effective than that of quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid.

As detailed above, according to the present invention, (2R.4R)-4-alkyl-2-piperidinecarboxylic acid useful as an intermediate for anticoagulant agents can be obtained in high yield and with high purity.

The present invention will be explained below with reference to Examples.

Note that 4-alkyl-2 used in the examples
-Piperidinecarboxylic acid and its alkyl ester were synthesized according to the method described in Japanese Patent Application No. 150064/1983.

Example 1 (A) Separation of trans and cis isomers from ethyl 4-methyl-2-piperidine carboxylate The cis and trans isomers were separated by vacuum distillation.

Trans form Boiling point 85~7℃/7mmHg Cis form Boiling point 107~8℃~5mmHg (B) Optical resolution of trans form Ethyl 4-methyl-2-piperidinecarboxylate (trans form 99.7%, cis form 0.3
%) The racemate is refluxed in excess concentrated hydrochloric acid for 4 hours and then the hydrochloric acid is distilled off to give 4-methyl-2-piperidinecarboxylic hydrochloride. 4-Methyl-2-piperidinecarboxylic hydrochloride was added to an ion exchange resin (Diaion SK-
112 (trade name, manufactured by Mitsubishi Chemical Industries, Ltd.) to obtain a racemic form of 4-methyl-2-piperidinecarboxylic acid. This racemic body, 143.2g is 95
% ethyl alcohol, 150 g of L-tartaric acid was added, and after cooling, the precipitated salt was filtered to obtain 145.9 g of crude crystals.

When the crude crystals are recrystallized from 1000 ml of 90% ethyl alcohol, (2R·4R)-4-methyl-2-piperidinecarboxylic acid-L-tartrate is obtained.
The physical properties of this product are as follows.

Melting point 183.9-185.0℃ [α] ²⁶ _D = +4.4 (C = 10in H ₂ O) Elemental analysis value C ₁₁ N ₁₉ NO ₈ Calculated value 45.05 6.53 4.77 Actual value 45.12 6.48 4.70 By X-ray diffraction, This compound is (2R・4R)-4
-It is a 1:1 compound of methyl-2-piperidinecarboxylic acid and L-tartaric acid.

This compound was eluted with a 3% aqueous ammonium hydroxide solution using 2000 ml of ion exchange resin (Diaion SK-112) according to a conventional method, and when the solvent was distilled off, 63.0 g of (2R・4R)-4-methyl -2-
Piperidine carboxylic acid was obtained in powder form. The physical properties of this compound recrystallized from ethyl alcohol-water are shown below.

Melting point 275.0-277.8℃ [α] ¹⁸ _D = -18.0 (C = 10in 2N-HCl) Elemental analysis value C ₇ H ₁₃ As NO ₂ C H N Calculated value 58.72 9.15 9.78 Actual value 58.80 9.09 9.71 Contains optical enantiomer Concentrate and dry the mother liquor,
It was treated in the same manner as described above to obtain 64.6 g of (2S·4S)-4-methyl-2-piperidinecarboxylic acid. The physical property values are as follows.

Melting point 275.0-277.8℃ [α] ²⁴ _D = +17.8 (=10in 2NHCl) Elemental analysis value C ₇ H ₁₃ NO ₂ Calculated value 58.72 9.15 9.78 Actual value 58.82 9.10 9.69 Example 2 4-Methyl-2 -Piperidinecarboxylic acid 225.7
480 ml of water was added to 236.2 g of L-tartaric acid (trans isomer 77.2%, cis isomer 22.8%) and dissolved with heating, 420 ml of water was distilled off, and ethyl alcohol 3 was added while heating. After stirring at room temperature for 1 hour and further stirring for 2 hours under ice cooling, the precipitated crystals were collected. The crystals were dissolved in 220 ml of water under heating, 50 ml of water was distilled off, and 1.5 ml of ethyl alcohol was added under stirring under heating to recrystallize, yielding 173.1 g (97%) of (2R・4R)-4-methyl-2-piperidinecarvone. Obtain addition salt.

Melting point 183-185℃ [α] _D = +4.6 (C = 10 in H ₂ O) 76 g (90 in.
%) of (2R·4R)4-methyl-2-piperidinecarboxylic acid is obtained.

Melting point 275-277.5℃ [α] ¹⁸ _D = -17.9 (C = 10in 2N HCl) Example 3 (2R・4R)-1-[N ² -(3-methyl-1・2・
Production of 3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid.

(A) Synthesis of ethyl (2R・4R)-4-methyl-2-piperidinecarboxylate 51.6 g of (2R・4R)-4-methyl)-2-piperidinecarboxylic acid was dissolved in anhydrous ethyl alcohol for 30 minutes.
Thionyl chloride 128.6 with stirring below ℃
g was added dropwise, and the mixture was allowed to react at room temperature for 1 hour and then for another 1 hour under reflux. The solvent was distilled off and the residue was dissolved in benzene.
Dissolve in 500 ml, wash with 100 ml of 5% potassium carbonate and 200 ml of saturated saline, and dry over anhydrous sodium sulfate. When the benzene was distilled off and the remaining liquid was vacuum distilled, 57.4g of ethyl (2R・4R)-4
-Methyl-2-piperidinecarboxylate was obtained. The physical properties are as follows.

Boiling point 83-85℃/7mmHg [α] ²² _D = -24.0 (C = 5in ethyl alcohol) Elemental analysis value C ₉ H ₁₇ As NO ₂ C H N Calculated value 63.13 10.00 8.18 Actual value 63.20 9.96 8.12 (B) Ethyl ( 2R・4R)-1-[N ^G -Nitro-N ²
-(tert-butoxycarbonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylate 28.5 g of N ^G -nitro-N ² -(tert-butoxycarbonyl)-L-arginine are dissolved in 450 ml of anhydrous tetrahydrofuran. While maintaining the solution at -20°C and stirring, 9 g of triethylamine was added followed by 12.2 g of isobutyl chloroformate.
Add. After 10 minutes, add more ethyl (2R/4R)-4
-Methyl-2-piperidinecarboxylate
Add 15.2 g and stir the mixture for 10 minutes at -20°C. At this point the reaction mixture was warmed to room temperature and
The solvent is evaporated off and the residue is dissolved in 400 ml of ethyl acetate. It is then washed successively with 200 ml of water, 100 ml of 5% sodium bicarbonate solution, 100 ml of 10% citric acid solution, and 200 ml of water, and the ethyl acetate solution is dried over anhydrous sodium sulfate. 31.3g when ethyl acetate is distilled off
(74.5%) of ethyl (2R・4R)-1-[N ^G -nitro-N ² -(tert-butoxycarbonyl)-L-
[Arginyl]-4-methyl-2-piperidinecarboxylate was obtained in the form of a syrup.

IR (KBr): 3300, 1730, 1680 cm ^-1 (C) Ethyl (2R・4R)-1-(N ^G -nitro-L-
Arginyl)-4-methyl-2-piperidinecarboxylate hydrochloride Ethyl (2R・4R)-1-[N ^G -nitro-N ²
30 g of -(tert-butoxycarbonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylate is dissolved in 30 ml of ethyl acetate, and 80 ml of 10% anhydrous hydrogen chloride-ethyl acetate is added at 0 DEG C. with stirring. After 3 hours, 200 ml of anhydrous ethyl ether was added to the solution, resulting in a viscous oil. When this substance is filtered and washed with anhydrous ethyl ether, (2R・4R)-1-
[N ^G -Nitro-L-arginyl)-4-methyl-2-piperidinecarboxylate hydrochloride was obtained as an amorphous solid.

(D) Ethyl (2R・4R)-1-[N ^G -nitro-N ²
-(3-methyl-8-quinolinesulfonyl)-L
-Arginyl]-4-methyl-2-piperidinecarboxylate Ethyl (2R・4R)-1-(N ^G -nitro-L-
25 g of (arginyl)-4-methyl-2-piperidinecarboxylate hydrochloride was added to 200 g of chloroform.
18.5 g of triethylamine and 14.7 g of 3-methyl-8-quinolinesulfonyl chloride are sequentially added thereto while stirring and maintaining the temperature at 5° C., followed by stirring at room temperature for 3 hours. After stirring, the solution is washed twice with 50 ml of water and dried over anhydrous sodium sulfate. After removing the solvent by evaporation, chromatography was performed using 50 g of silica gel to reduce the concentration to 3%.
Elution was performed with methanol-chloroform. When the eluted solvent was distilled off, 32.5 g (92.1%) of ethyl (2R・4R)-1-[N ^G -nitro-N ² (3-methyl-8-quinolinesulfonyl)-L-arginyl]-4- Methyl-2-piperidine carboxylate was obtained as a solid.

IR (KBr): 3250, 1725, 1640cm ^-1 (E) (2R・4R) -1-[N ^G -Nitro-N ² -(3-
Ethyl (2R・4R)-1-[N ^G -nitro-N ²
(3-methyl-8-quinolinesulfonyl)-L-
32.5 g of [arginyl]-4-methyl-2-piperidine carboxylate and 100 ml of ethanol and 1N
Dissolve in 100 ml of aqueous sodium hydroxide mixed solvent and stir at room temperature for 24 hours. Then neutralize with 1N hydrochloric acid and concentrate to 70ml. The solution was adjusted to pH 11 with 1N sodium hydroxide and ethyl acetate 100%.
ml Then wash with 100 ml of chloroform and acidify with 1N hydrochloric acid. The resulting precipitate was filtered, washed with 20 ml of water, and 27 g (95%) of (2R・4R)-1-[N ^G
-Nitro- ^N2- (3-methyl-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2
-Piperidinecarboxylic acid was obtained.

Melting point 211 - 213℃ IR (KBr): 3280, 1720, 1620 cm ^-1 Elemental analysis value C ₂₃ H ₃₁ N ₇ O ₇ As C H N Calculated value 50.26 5.69 17.84 Actual value 50.05 5.45 17.45 (F) (2R・4R )-1-[N ² -(3-methyl-1.
2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-
Piperidinecarboxylic acid (2R・4R)-1-[N ^G -nitro-N ² -(3-
Dissolve 3.0 g of methyl-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid in a mixed solvent of 40 ml of ethanol and 10 ml of acetic acid, and add 0.3 g of 5% Pd/C.
The mixture was shaken at 80° C. for 4 hours under a hydrogen pressure of Kg/cm ² . The catalyst is then removed by filtration and the solvent is removed by evaporation. The resulting viscous oil was extracted with a mixture of 30 ml of chloroform and 30 ml of saturated sodium bicarbonate solution, the chloroform layer was washed with 30 ml of water, the chloroform was removed by evaporation, and the resulting crude crystals were recrystallized from ethanol. g (94%)
(2R・4R)-1-[N ² -(3-methyl-1・
2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-
Piperidine carboxylic acid was obtained.

Melting point 188-191℃ NMR 100MHz Solvent CD ₃ OH δ value 6.5 (Triplet 1H) 7.1 (Doublet 1H) 7.4 (Doublet 1H) Elemental analysis value C ₂₃ H ₃₆ N ₆ O ₅ S C H N Calculated value 54.31 7.13 16.52 Actual measurement Value 54.01 6.98 16.61 Example 4 (2R・4R)−[N ² −(3-methyl-1・2・3・
4-tetrahydro-8-quinolinesulfonyl)
-L-Arginyl]-4-Methyl-2-piperidinecarboxylic acid Measurement of pharmacological effects Pharmacological tests were conducted as follows.

A solution of 150 mg of bovine fibrinogen (Cohn Fraction 1, manufactured by Armour) dissolved in 40 ml of Borate Saline Buffer (PH7.4).
Mix 0.8 ml and 0.1 ml of borate saline buffer (control sample) or sample solution under ice cooling, and then add 5 units/ml of thrombin (reagent manufactured by Mochida Pharmaceutical Co., Ltd.).
Add 0.1ml under ice-cooling, mix well and immediately bring to 25°C.
Transfer to a constant temperature bath. A stopwatch was started the moment it was placed in the thermostatic bath, and the time until fibrin was observed was measured. When no sample was added (control experiment), the clotting time was 50-55 seconds.

By the above method, (2R・4R)-[N ² -(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-
The concentration of 2-piperidine carboxylic acid that doubled the clotting time, ie, the concentration required to increase the clotting time from 50-55 seconds to 100-110 seconds in the control experiment, was 0.02 μM. On the other hand (2S/4S) -1-
For [N ² -(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid, it was 70 μM.

Claims (1)

[Claims] 1. L-tartrate of (2R・4R)-4-alkyl-2-piperidinecarboxylic acid is obtained by contacting 4-alkyl-2-piperidinecarboxylic acid with L-tartaric acid in water or an aqueous solvent, and if necessary, (2R·4R)-4-alkyl-2-, characterized in that L-tartrate is desorbed and removed from the L-tartrate by
A method for producing piperidine carboxylic acid or its L-tartrate.