Palladium-Catalyzed Annulation via Acyl C–H Bond Activation

Palladium-catalyzed annulation of ortho-bromobenzaldehydes with aryl diazoesters is achieved via a sequence of palladium carbene migratory insertion, acyl C–H bond activation and reductive elimination of a seven-membered palladacyclic intermediate. A variety of isocoumarin derivatives were furnished in a straightforward manner.