Recent Advances in Transition Metal-catalyzed Functionalization of gem-Difluoroalkenes

gem-Difluorinated alkenes are readily accessible building blocks that can undergo functionalization to provide a broad spectrum of fluorinated and non-fluorinated products. Herein, we review recent (since 2017) transition metal-catalyzed transformations of these specialized alkenes and summarize general reactivity patterns of these reactions. Many transition metal-catalyzed reactions undergo net C-F bond functionalization reactions to deliver monofluorinated products. These reactions typically proceed through beta-fluoroalkylmetal intermediates that readily eliminate a beta-fluoride to deliver monofluoroalkene products. A second series of reactions exploit coinage metal fluorides to add F- to the gem-difluorinated alkene, and further functionalization delivers trifluoromethyl-containing products. In stark contrast, few transition metal-catalyzed reactions proceed in net fluorine-retentive processes to deliver difluoromethylene-based products.