Direct Functionalization of Unactivated C(sp 3 )H Bonds via Photocatalyzed Hydrogen Atom Transfer

Abstract The direct and selective functionalization of unactivated C(sp 3 )H bonds is one of the most attractive goals in synthetic chemistry. While the radical‐mediated hydrogen atom transfer (HAT) process has shown considerable potential in such reactions, it faces fundamental problems associated with reactivity and selectivity. This chapter describes the strategies of indirect HAT ( i ‐HAT) and direct HAT ( d ‐HAT) photocatalysis developed for C(sp 3 )H functionalization in unactivated aliphatic hydrocarbons and remote C(sp 3 )H feedstocks. A number of examples demonstrate the advantages of HAT photocatalysis for the initiation of radical processes in a mild and controllable manner, which can help to achieve useful chemo‐, site‐, and stereoselectivity. Combination of such reactions with asymmetric catalysis, offering appealing opportunities to furnish chiral products from the most abundant starting materials, is discussed. Such advances in this methodology will stimulate further progress in diversity‐oriented synthesis, catalysis, pharmaceutics, and material science.