Synthesis of tetrathiafulvalene by photoinduced electron-transfer reactions.

A novel photochemical synthetic route to tetrathiafulvalene, starting from 1, 3-dithiole-2thione is described. Irradiation of 4, 5-diphenyl-1, 3-dithiole-2-thione in the presence of triethyl phosphite or triethylamine in acetonitrile gave tetraphenyltetrathiafulvalene in 91%or 53% yield, respectively. The photoinduced electron transfer from the phosphite to the 1, 3-dithiole-2-thione apparently accelerates the phosphite-promoted coupling of the 1, 3dithiole-2-thione.