alpha-Palladation of Imines as Entry to Dehydrogenative Heck Reaction: Aerobic Oxidative Cyclization of N-Allylimines to Pyrroles

We report here a palladium(II)-catalyzed oxidative cyclization reaction of N-allylimines derived from methyl ketones, typically acetophenones, affording pyrrole derivatives at room temperature under oxygen atmosphere. The reaction likely proceeds through alpha-palladation of the imine followed by olefin migratory insertion and beta-hydride elimination, thus representing a new example of aerobic dehydrogenative Heck cyclization.