Stoichiometric couplings of methylarenes through visible-light-induced bromo radical formation from aryl halides

Abstract

A visible-light/nickel dual catalyzed stoichiometric coupling of methylarenes via bromine radical-enhanced HAT has been developed. Aryl bromides serve as both cross-coupling partners and bromine radical precursors. Mechanistic studies reveal that the bromine radical acts as a highly efficient HAT reagent to abstract the benzylic C(sp³)–H bond to deliver a benzylic radical and subsequently engages in Ni-catalyzed arylation couplings. The synthetic utility of this approach is further proved by its application in the late-stage arylation or benzylation of several drug-like and complex molecules in a stoichiometric manner.