PURPOSE:To produce the titled compound useful as a raw material of pharmaceuticals, etc., easily, in high yield, without causing racemization, by hydrolyzing an optically active thiazolidine-4-carboxylic acid in the presence of a carbonyl reagent or a metal bisulfite. CONSTITUTION:An optically active cysteine is produced by hydrolyzing an optically active thiazolidine-4-carboxylic acid in the presence of a carbonyl reagent or a metal bisulfite. The hydrolysis is carried out in an aqueous solution, preferably in an aqueous solution of a mineral acid such as sulfuric acid, hydrochloric acid, etc. in the presence of a compound (e.g. sodium sulfite) to capture formaldehyde generated by the hydrolysis. The amount of the formaldehyde acceptor is >=1mol, preferably about 1.3-10mol per 1mol of the optically active compound.

Tashiro Yasuhisa

Papers

Production of optically active cysteine