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

By combining N-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 N-centered succinimidyl radical, which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr(center dot)-Mes.