SU586168A1 - Method of isolating a-amino-substituted isomer from mixture of a and b-amino-b(a)alkylthiocarboxylic acid derivatives - Google Patents

Description

100 mg of acetyl (0.24 g, 0.003 mol) in 10 ml of absolute ether. Then a 1M ethereal solution of hydrogen chloride is added until acidic, and the anilide p- (M-acetylamino) -a-phenylthioisobutyric acid and the mixture of anilides a-and p-amino-p (a) -phenylthionzoma are separated in the form of a precipitate. acids. The precipitate is filtered off and washed with water. Anilide | 3- (N-acetylamino) -a-phenylthioisobutyric acid remains in the sediment, the yield is 73.5%, and a mixture of anilides hydrochloride and p - amino - p (a) - phenylthioisobutyric acids is contained in the aqueous solution. An aqueous solution of sodium carbonate is added to the resulting solution until alkaline, the resulting free amino derivatives are extracted with ether and dried with magnesium sulfate. The ether is distilled off in vacuo to give 2.06 g (0.0072 mol) of a mixture of anilides (OC- and p-amino-p (a) -phenylthioisobutyric acids (90:10). To completely separate the isomers. The process is repeated as described above. 1.89 g (0.0065 mol) of a-amino-p-phenylthioisobutyric acid anilide is obtained, yield 93%. Found: C, 67.17; H, 6.20; N, 9.91; S 10; 90. CigHisNaOS Calculated,%: C 67.13; H 6.29; N 9.79; S 11.19. The structures of anilides a- and p-amino-p- and afenilthiobutyric acids were also confirmed by PMR spectra. R-22 NMR spectrometer with an operating frequency of 90 MHz. Example 2. 1.1 g (0.0036 mol) of anilide a (p) amino-p (: ) - benzylthioisobutyric acid, containing 49% of the a-amino-isomer isomer, is dissolved in 40 ml of absolute ether and 0.13 g (Ou0016 mol) of acetyl chloride in 10 ml of ether is added with stirring and cooling. , the crystalline precipitate is filtered off, the solution is evaporated and 0.12 g (0.0004 mol) of a mixture of anilides a (p) amino-p (yc) -benzylthioisobutyric acid is isolated. The crystalline precipitate is partially dissolved in water, sodium carbonate solution is added until alkaline, extracted with ether, dried, evaporated in vacuo, and 0.34 g (0.0011 mol) of a-amino-p-benzylthioisobutyric acid is isolated. The undissolved precipitate is dried in a vacuum desiccator and extracted with carbon tetrachloride. According to the PMR spectra data, the precipitate consists of anilide P- (N-acetylamino) -a-benzylthioisobutyric acid. When the mixture of anilides a (p) -amino-p (a) -benzylthioisobutyric acid is re-separated, another 0.06 g (0.0002 mol) of a-amino-p-benzylthioisobutyric acid anilide is isolated. Overall yield 74.2%. The individuality of the compounds is determined by microanalysis and PMR spectra taken on an R-22 NMR spectrometer with a frequency of 90 MHz. In tab. Figure 1 shows the microanalysis data for ailides a (P) -amino-p (a) -benzylthioisobutyric acid and P- (N-acetylamino) -a-benzylthioisobutyric acid anilide.

Example 3. 0.68 g (0.003 mol) of anilide a (p) -amino-p (a) -methylthioisobutyric acid (40:60) is dissolved in 50 ml of absolute ether, 0.31 g (0.0031 mol of triethylamine; and with vigorous stirring, 0.14 g (0.0018 mol) of acetyl chloride in 20 ml of absolute ether is added. Hydrogen chloride in ether is added to the mixture until acidic. The filtrate is evaporated in vacuo and 0.42 g (0.0016 mol) of p- (N-acetylamino) -a-methylthioisobutyric acid anilide is isolated. The precipitate is treated with a solution of carbonate nTab .1 and ca 1

three and extracted with ether. The ether solution is separated, dried with magnesium sulfate, evaporated in vacuo to give 0.2 g (0.0009 mol) of anilide of α-amino-p-methylthioisobutyric acid, yield 75%.

The purity of the compounds is determined. according to microanalysis and PMR spectra, taken on

R-22 NMR spectrometer with an operating frequency of 90 MHz.

In tab. 2 shows the microanalysis data of anilides a (P) -amino-p (a) methylthioisobutyric acid and p- (N-acetylamino) -. Os-methylthioisobutyric acid anilide.

Claims (1)

Invention Formula The method of separation of a-amino-substituted isomer from a mixture of derivatives of a- and p-aminor of (a) alkylthiocarboxylic ki-slot RI Kz I 1 RZ-C-C-COX (I)  SS (SH) (Zhg) where Ri, R2, Hz is hydrogen or methyl; R4 is methyl, phenyl or benzyl; X is NHCeHs- or methoxy; table 2 characterized in that, in order to simplify the process, a mixture of derivatives of a- and p-amino-p (a) alkylthiocarboxylic acids is dissolved in B absolute ether, an equimolecular amount of acetyl chloride calculated for p-amino-isomer is added, after an ether solution of hydrogen chloride is added to the acidic reaction, the precipitate is filtered, washed with water, sodium carbonate solution is added to the alkaline reaction, extracted with ether and the desired product is isolated from the ether solution.