Aerobic Benzylic C(sp3)–H Bond Oxygenations Catalyzed by NBS under Visible Light Irradiation

An efficient photocatalytic oxidation of benzylic C(sp3)–H bonds to ketones, esters, and amides has been developed using NBS as a metal-free photocatalyst and O2 as an oxidant. A variety of synthetically and biologically valuable compounds are assembled in moderate to excellent yields. The synthetic utility of this approach has been demonstrated by gram-scale experiments. A possible free radical mechanism was proposed to rationalize the reaction procedure.