Palladium-Catalyzed Synthesis of Triphenylenes via Sequential C-H Activation and Decarboxylation

A novel tandem intermolecular decarboxylative coupling reaction of o-bromobenzoic acids and aryl iodides has been developed. The method affords a range of unsymmetrically triphenylenes and displays unique regioselectivity and broad substrate scope. Mechanistically, palladium/norbornene-catalyzed C-H activation and subsequent double decarboxylative coupling reactions were involved. Moreover, the triphenylenes can also be synthesized from 2-iodobiphenyls and o-bromobenzoic acids under norbornene-free conditions.