Carbofluorination of Alkenes with gem-Difluorinated Cyclopropanes as Bifunctional Reagents Enabled by Well-Define Rhodium Catalysts

Herein, we report a Rh-catalyzed carbofluorination of alkenes using gem-difluorinated cyclopropanes as bifunctional reagents. The developed method tolerates a wide range of alkenes, providing access to secondary, tertiary fluorides and gem-difluorides with 100% atom-economy under mild conditions. The resulting fluorides can be further transformed to yield C−C, C−N, and C−O bifunctionalization products. Cationic dicarbonyl rhodium tetrafluoroborate has been identified to be the only highly efficient catalyst in this reaction. Preliminary mechanistic studies reveal that the addition of fluorine atom to alkenes is mediated by tetrafluoroborate ion, which acts as a fluorine anion shuttle.