Synthesis of gem-Difluoroalkenes via Zn-Mediated Decarboxylative/Defluorinative Cross-Coupling

An efficient and mild Zn-mediated decarboxylative/defluorinative alkylation of alpha-trifluoromethyl alkenes using N-hydroxyphthahmide esters as radical precursors was developed. Several a-trifluoromethyl alkenes were readily coupled to a wide range of primary, secondary, and tertiary radicals, affording the desired gem-difluoroethylenes in moderate to excellent yields. This reaction protocol was also successfully applied to the construction of complex molecules such as the bioactive natural dehydroabietic acid and glycosyl groups bearing the gem-difluoroethylene moiety.