Regiodivergent Synthesis of gem-Difluoroalkenes Enabled by Electron Donor-Acceptor Complex-Mediated C–F Bond Photoreduction of α-Trifluoromethyl Styrenes

gem-Difluoroalkenes are valuable carbonyl bioisosteres in medicinal chemistry. Conventional synthesis primarily involves nucleophilic addition to α-trifluoromethyl styrenes. In contrast, recent approaches leverage photocatalytic radical addition, followed by reduction and fluoride elimination. Reaction pathways utilizing gem-difluoroallyl radicals remain largely underdeveloped despite their potential to enhance synthetic diversity. We report herein an electron donor-acceptor (EDA) complex-mediated C-F bond photoreduction of αtrifluoromethyl styrenes for the synthesis of gem-difluoroalkenes via gem-difluoroallyl radical addition. Radical trapping experiments confirm the formation of gem-difluoroallyl radical intermediates. By integrating this radical pathway with a conventional nucleophilic addition strategy, regiodivergent synthesis of gem-difluoroalkenes is achieved. To the best of our knowledge, this work is the first example of C–F bond photoreduction and functionalization of α-trifluoromethyl styrenes via gem-difluoroallyl radicals, forming gem-difluoroalkenes.