Photochemical and Electrochemical Strategies towards Benzylic C−H Functionalization: A Recent Update

Transition metal-catalysed processes have been widely used for the functionalization of inert C−H bonds. Strategies for the functionalization of the benzylic C−H position having a relatively weak C−H bond (bond dissociation energy∼ 80–90 kcal/mol) differ from the inert aliphatic and aromatic C−H positions with stronger C−H bonds. The recent advances in the direct activation of the benzylic position through the generation of C(sp3) radicals have demonstrated the potential of electrochemistry and photochemistry as a means for constructing new chemical bonds. This review will cover the recent progress of benzylic C−H functionalization through organic radical strategies employing photochemistry and electrochemistry as sustainable tools. In addition, the mechanistic details of the typical reactions have been included which, in turn, will help the researchers to look at this promising area from a different perspective towards new discoveries and often hidden opportunities. (Figure presented.). © 2021 Wiley-VCH GmbH