The Reaction of 5-Unsubstituted-1,2-Dithiole-3-thiones with some Activated Acetylenes

Abstract

5-Unsubstituted 1,2-dithiole-3-thiones undergo addition reactions with dimethyl acetylenedicarboxyl-ate and dibenzoylacetylene to give amorphous 2-thioformylmethylene-1,3-dithioles. In certain cases these may undergo further addition of activated acetylene to give thiopyranspiro-1,3-dithioles, but may also lose sulfur to give bis-1,3-dithiolylidene-2-butenes, which are probably formed via initial dimerization of the thioformylmethylenedithioles. The stereochemistry of the products is discussed briefly.