Visible Light-Catalyzed Benzylic C–H Bond Chlorination by a Combination of Organic Dye (Acr⁺-Mes) and <i>N</i>-Chlorosuccinimide

Abstract

By combining "<i>N</i>-chlorosuccinimide (NCS)" as the safe chlorine source with "Acr⁺-Mes" as the photocatalyst, we successfully achieved benzylic C-H bond chlorination under visible light irradiation. Furthermore, benzylic chlorides could be converted to benzylic ethers smoothly in a one-pot manner by adding sodium methoxide. This mild and scalable chlorination method worked effectively for diverse toluene derivatives, especially for electron-deficient substrates. Careful mechanistic studies supported that NCS provided a hydrogen abstractor "<i>N</i>-centered succinimidyl radical," which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr^•-Mes.