Photochemical C-H bond coupling for (hetero)aryl C(sp2)-C(sp3) bond construction.

Alkylated (hetero)arenes constitute one of the most fundamental skeletons in organic molecules, which prompts a growing number of research studies on the construction of (hetero)aryl C(sp2)-C(sp3) bonds especially using C-H bonds of feedstocks. With the flourishing resurgence of photoredox catalysis in organic synthesis, fruitful achievements have been witnessed in photochemical (hetero)aryl C(sp2)-C(sp3) bond formation through C-H bond coupling such as (hetero)arylation of C(sp3)-H bonds and alkylation of (hetero)aryl C(sp2)-H bonds. Photoinduced generation of alkyl radicals from various alkylating agents is the key point to the success of these reactions. This review will summarise advances in this area with emphasis on the reaction mechanisms.