Thioacylketene thioacetals (7) and N-Thioacyldithioimidocarbonates (8) undergo 1,4-cycloaddition reactions with active acetylenes and olefins to give six-membered heterocycles. Tetracyanoethylene behaves in a different way to afford conjugated dienes. In the reactions with diphenylketene and diazo compounds, 7 and 8 undergo different types of reactions; 7 gave products derived from 1,2-cycloaddition