Tandem Photocyclization-Intramolecular Addition Reactions of Aryl Vinyl Sulfides. Observation of a Novel Cycloaddition-Allylic Sulfide Rearrangement

Article abstract of DOI:10.1021/jo00030a022

Photocyclization of aryl vinyl sulfides reportedly proceeds via thiocarbonyl ylide intermediates.The photochemical behavior of several aryl vinyl sulfides, which incorporate a pendant alkene side chain, was explored.In general, naphthyl and phenyl vinyl thioethers provided products which are consistent with photocyclization to a thiocarbonyl ylide intermediate followed by either intramolecular hydrogen shift or subsequent intramolecular ylide-alkene addition.Product distribution is influenced by solvent and and temperature effects.Novel secondary photoprocesses were also observed during some reactions.Thus, irradiation of naphthyl vinyl sulfide 20 gave dihydrothiophene 22 which underwent subsequent intramolecular <2 + 2> cycloaddition to provide 24.Upon prolonged irradiation 24 undergoes a novel allylic sulfide rearrangement to provide 25.