Coformational aspects of polypeptide structure XL. The synthesis of poly((S)-thiazolidine-4-carboxylic acid)

The synthesis of poly(S)-thiazolidine-4-carboxylic acid] is described. The polymer is obtained by the polymerization of the N-carboxyanhydride of (S)-thiazolidine-4-carboxylic acid in pyridine or nitrobenzene using triethylamine as an initiator. The amino acid is prepared by the condensation of cysteine and formaldehyde. N-Acetyl-(S)-thiazolidine-4-carboxylic acid methyl ester is also prepared as a model compound by standard acetylation and esterification reactions.