Thiobenzoic acid–catalyzed radical–radical cross–coupling between benzyl alcohols and benzophenones via hydrogen atom transfer

Abstract

The radical-radical cross-coupling of benzyl alcohols with benzophenones was successfully demonstrated by using thiobenzoic acid as a multifunctional photocatalyst. The reaction proceeded smoothly under visible-light irradiation to afford the corresponding diols in good yield and various functional groups were well tolerated. Furthermore, the catalytic system was also applicable to prenyl alcohol and benzylamine. Mechanistically, the excited state of thiobenzoate acts as a single electron reducing agent for benzophenones and the resulting sulfur radical promotes hydrogen atom abstraction from benzyl alcohols.