“…Mixed anhydride (67), prepared by passing ketene into chloroacetic acid, reacts with substituted and unsubstituted thioureas in chloroform at 60 °C to give various 2-imino-4-thiazolidinoneslu'112 (68). Various 3-substituted-2-thiono-4-thiazolidinones (69) can be conveniently prepared by the reaction of substituted isothiocyanates with a-mercaptoacetic acid or its ester followed by acid cyclization of the resulting (thiocarbamoyl)mercaptoacetic acids and acetates.113 amount of alcoholate to give 4-thiazolidinones147,148 (74).…”