Switching from gem-difluorovinylation to carboxylation: ligand-enabled palladium-catalyzed Heck annulation of alkene-tethered aryl halides with sodium difluorochloroacetate

The use of a ligand to tune palladium-catalyzed intramolecular Heck gem -difluorovinylation and carboxylation is reported. Sodium difluorochloroacetate (ClCF 2 COONa) acts as both a difluorocarbene (:CF 2 ) and carboxyl source.