Direct HAT: a complementary paradigm for activating α-silyl alcohols in enantioconvergent radical-relay coupling

Abstract

The direct HAT activation of alcohols for alkoxy radical generation is impeded by high O–H bond strengths, and prevailing photochemical methods are limited by substrate redox potentials or metal-dependent activation requirements. Herein, we introduce a complementary paradigm leveraging the β-silicon effect in α-silyl alcohols to weaken the O–H bond, enabling its redox-neutral, photoinduced homolysis via thioxanthone. Subsequently, the generated alkoxy radicals undergo facile Brook rearrangement to produce carbon radicals, which are intercepted by a nickel catalyst in enantioconvergent cross-couplings with acyl chlorides and aryl bromides. This protocol provides diverse chiral acylons and alcohols with high enantioselectivity. It tolerates substrates that are inert under classical SET/PCET conditions and establishes direct HAT as a versatile platform for alkoxy radical chemistry of α-silyl alcohols.