Organo-photoredox-Catalyzed Atom-Transfer Radical Substitution of Alkenes with α-Carbonyl Alkyl Halides.

A light-driven atom-transfer radical substitution (ATRS) and carboesterification reaction of alkenes with alkyl halides has been developed using PTH as the organo-photoredox catalyst. Two types of products were obtained, depending on the additive and solvent used during the reaction. Primary, secondary, and tertiary alkyl halides reacted to give the ATRS products. This protocol has several advantages: it requires mild reaction conditions and a low catalyst loading and exhibits a broad substrate scope and good functional group tolerance. Mechanistic studies indicate that alkyl radicals might be generated as the key intermediates via photocatalysis, providing a new direction for ATRS reactions.