Functionalization of C‐H Bonds by Photoredox Catalysis

Visible‐light photoredox catalysis has been successfully used in the functionalization of inert C−H bonds including C(sp2)‐H bonds of arenes and C(sp3)‐H bonds of aliphatic compounds over the past decade. These transformations are typically promoted by the process of single‐electron‐transfer (SET) between substrates and photo‐excited photocatalyst upon visible light irradiation (household bulbs or LEDs). Compared with other synthetic strategies, such as the transition‐metal catalysis and traditional radical reactions, visible‐light photoredox approach has distinct advantages in terms of operational simplicity and practicability. Versatile direct functionalization of inert C(sp2)‐H and C(sp3)‐H bonds including alkylation, trifluoromethylation, arylation and amidation, has been achieved using this practical strategy. Visible‐light photoredox‐catalyzed functionalization of inert C−H bonds including C(sp2)‐H bonds of arenes and C(sp3)‐H bonds of aliphatic compounds has been reviewed.