Racemization of Optically Active Cysteine via Formation of 2,2-Dimethyl-4-thiazolidinecarboxylic Acid

Optically active cysteine (Cys) was racemized via formation of (RS)-2,2-dimethyl-4-thiazolidinecarboxylic acid ((RS)-DMT) by refluxing in the presence of acetone in 10-fold molar amount in acetic acid. The formed (RS)-DMT was hydrolyzed by adding water to the reaction mixture to give (RS)-Cys in 95–97% yield.