Synthesis of <i>gem</i>-Difluoroalkenes via Cobalt-Catalyzed Alkylation of α-Trifluoromethyl Alkenes with α-Chloro Esters

Cobalt-catalyzed alkylation of α-trifluoromethyl alkenes with α-chloro esters has been developed. This reaction provides an efficient approach for the synthesis of <i>gem</i>-difluoroalkenes featuring a broad substrate scope and good yields under mild conditions. The practical applicability has been shown by the gram-scale synthesis and subsequent derivatization of the products. Furthermore, the preliminary mechanistic studies demonstrated that cobalt promotes the generation of alkyl zinc reagents from zinc powder and α-chloro esters, which attack the α-trifluoromethyl alkenes and ultimately yield the target products.