Photoinduced Synthesis of gem-Difluorinated Sulfides from Organic Thiocyanates via Difluorinated Phosphonium Salts.

A two-step strategy toward the synthesis of gem-difluorinated sulfides from organic thiocyanates is described. The first step consists in nucleophilic attack of the unstable difluorinated phosphorus ylide, generated from difluorocarbene and triphenylphosphine, at the sulfur atom of organic thiocyanates, affording difluorinated phosphonium salts as the key intermediate compounds. The latter are directly utilized as sources of thiodifluoromethyl radicals in the photoinduced Giese-type process and other transformations.