General Defluoroalkylation\nof Trifluoromethylarenes\nwith Both Electron-Donating and -Withdrawing Alkenes

The\nincorporation of gem-difluoromethylene units into organic molecules\nremains a formidable challenge. Conventional methodologies for constructing\naryldifluoromethyl derivatives relied on the use of high-functional\nfluorinating regents under harsh conditions. Herein, we report general\nand efficient photoredox catalytic systems for defluoroalkylation\nof readily available trifluoromethylarenes through selective C–F\ncleavage to deliver gem-difluoromethyl radicals which proceed through\nreductive addition to both electron-donating and withdrawing alkenes\nunder transition-metal free conditions. Mechanistic studies reveal\nthat thiol serves as both photocatalyst and HAT reagent under visible\nlight irradiation. This synergistic photocatalysis and HAT catalysis\nprotocol exhibits ample and salient features such as high chemo- and\nregioselectivity, broad substrate scope, amenable gram-scale synthesis\nand late-stage modification of bioactive molecules.