NOVEL METHODS FOR THE SYNTHESIS OF 3-ARYLMETHYL-4-THIAZOLIDINE CARBOXYLIC ACID-2-THIONES AND THEIR METHYL-ESTERS

Reductive amination, using benzaldehyde derivatives and sodium borohyd ride, on L-cystine yields N,N'-di (arylmethyl) cystines 7a-c which can be converted into N,N'-di(arylmethyl) cystine dimethyl esters 8a-c by esterification. The reductive reaction by zinc, hydrochloric acid and methanol on the derivatives 7 and 8 yields the thiols 4a-c and 5a-c, respectively which on reaction with CS2 or EtOCS2K are further convert ed into 3-arylmethyl-4-thiazolidine carboxylic acid-2-thiones 1a-c and their methyl esters 2a-c. Compounds 2a-c are also produced by esterif ication of 1a-c. Fewer reaction steps and higher yields are the advant ages of these methods.