Efficient synthesis of 1,2,4-dithiazolidine-3,5-diones (dithiasuccinoyl-amines) and observations on formation of 1,2,4-thiadiazolidine-3,5-diones by related chemistry

Abstract An efficient synthesis of 1,2,4‐dithiazolidine‐3,5‐diones ( 1 ) from chlorocarbonylsulfenyl chloride ( 3 ) plus O ‐dimethylaminoethyl‐ N ‐alkyl or aryl thiocarbamates ( 4 ) has been worked out. In this synthesis, 1,2,4‐thiadiazolidine‐3,5‐diones ( 5 ) have been shown to arise as low‐level by‐products, and experiments were conducted to elucidate the mechanism of the side reaction. N,N ′‐Dimethyl‐1,2,4‐thiadiazolidine‐3,5‐dione ( 5a ) was prepared in one step from N,N ′‐dimethylurea plus 3 , or from 4a plus one equivalent of sulfuryl chloride. A general route to 5 involved reaction of equimolar amounts of isocyanates ( 6 ), isothiocyanates ( 7 ) and sulfuryl chloride followed by hydrolysis of intermediate 9 . Heterocycles reported have been characterized by nmr, ir, uv, ms, and hplc.