Tandem Palladium-Catalyzed N,C-Coupling/Carbonylation Sequence for the Synthesis of 2-Carboxyindoles

Tandem palladium-catalyzed N,C-coupling/carbonylation, under 10 atm of carbon monoxide and at 110 degrees C, is a novel and efficient method for the preparation of 2-carboxyindoles. The catalyst system tolerates a variety of functional groups, and the noted indoles were obtained in good isolated yields.