synthesis of 3-arylmethyl-4- thiazolidine-carboxylic acid-2-ones and 2-thiones

barium salts of dibenzylidene cystines 8a-c were obtained from the reaction of lcystine with benzaldehyde or its derivatives in the presence of barium hydroxide. their reduction with zinc and hydrochloric acid in methanol yielded the narylmethylcysteines ?9a-c?. these can, in turn, be converted by esterification into the methyl esters ?10 a-c. ?reaction of n, n'-carbonyl diimidazole (im co) or n, n'- thiocarbonyl diimidazole (im cs) with thiols 9a-c and 10a-c gave 3-arylmethy-4- thiazolidine-carboxylic acid-2-ones 3a-c or 2-thiones la-c and their methyl esters 4ac and 2a-c respectively. from the reaction of p s with 3-arylmethyl 4 thiazolidine crespectively acid-2-ones 3a-c and 4a-c the derivatives of 2-thiones 2a-c and la-c were obtained as well