Reaction of 3-aryl-2-cyanothioacrylamides with dimethyl acetylenecarboxylate, methyl propiolate, and N-phenylmaleimide

The reaction of cyanothioacrylamides with dimethyl acetylenedicarboxylate, methyl propiolate, and N-phenylmaleimide was studied. The reaction follows a cycloaddition pathway to give thiopyrans, irrespective of the electronic or spatial effects of the substituents in the thioamide group and in position 3 of the 1-thiabuta-1,3-diene system. The reaction is regio-and stereoselective.