Synthesis of Chromans by Photosensitized Electrochemical Oxidation of Sulfides Mediated by Methylene Blue.

Abstract o-Quinone methides were generated by a photosensitized cleavage of sulfides under neutral conditions using visible light provided by a 100 Watt spot light and methylene blue as a sensitizer. The key step in the oxidative cleavage is the transfer of one electron form the sulfide to the electronically excited visible dye. The resulting phenylthio radical cation undergoes frangmentation, and the correspondign o-quinone methides are generated and trapped by varied alkenes to yield chromans.