Treatment of 4-chloro-5H-1, 2, 3-dithiazol-5-one with 3-alkyl (or aryl)-3-amino-2-propenoate esters in DMSO at 120° C gave the corresponding 2-thiocyanated esters 4 (major) and 5- alkoxycarbonyl-4-alkyl (or aryl)-4-thiazolin-2-ones 5 (minor), whereas the esters bearing a