Palladium-catalyzed intramolecular Heck dearomative gem-difluorovinylation of indoles

Abstract

A palladium-catalyzed dearomative reaction of indoles has been developed through a domino Heck/gem-difluorovinylation sequence. By taking advantage of a difluorocarbene precursor (ClCF₂COONa), the palladium difluorocarbene ([Pd]CF₂) species was formed smoothly. Then, a migratory insertion/β-H elimination process enabled access to polycyclic indolines containing 1,1-difluoroethylene units in acceptable yields with a broad substrate scope, which also showed dearomative gem-difluorovinylation for the first time. Remarkably, the superb diversified transformations allowed the product to install various functional groups.