Reaction of sulfur ylides with elemental sulfur and selenium. Aspects and mechanistic considerations

Abstract The reaction of sulfur ylides with elemental sulfur or selenium initially affords thio‐ or seleno‐carbonyl compounds, which then react with starting ylides to give episulfides or episelenides from which the heteroatom (sulfur or selenium) is extruded to give olefins as the final product. In the case of carbonyl‐stabilized ylides, the resulting thio‐ or seleno‐carbonyl compounds react with starting ylides to afford 1,3‐oxathioles or 1,3‐oxaselenoles as previously reported. Supporting evidence for the intermediacy of thio(seleno)‐carbonyl compounds and episulfides (episelenides) is presented.