α-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 α-palladation of the imine followed by olefin migratory insertion and β-hydride elimination, thus representing a new example of aerobic dehydrogenative Heck cyclization.