Visible-light-induced Mn(0)-catalyzed direct C-3 mono-, di- and perfluoroalkylation reactions of 2 H -indazoles.

A general and efficient method for visible-light-driven fluoroalkylation, such as difluoromethylphosphonation, difluoroacetamidation, monofluoromethylation, difluoromethylation, and perfluoroalkyalation, of 2 H -indazoles using an inexpensive Mn 2 (CO) 10 photocatalyst has been developed. The present methodology affords a new series of C-3 fluoroalkylated 2 H -indazole derivatives with wide functional group tolerance in good to excellent yields. Difluoromethylenated indiazoles are also prepared from difluoroester derivatives. Our mechanistic investigations support a radical pathway for the reaction.