Regioselective Synthesis of Polycyclic and Heptagon‐embedded Aromatic Compounds through a Versatile π‐Extension of Aryl Halides

Abstract A versatile π‐extension reaction was developed based on the three‐component cross‐coupling of aryl halides, 2‐haloarylcarboxylic acids, and norbornadiene. The transformation is driven by the direction and subsequent decarboxylation of the carboxyl group, while norbornadiene serves as an ortho ‐C−H activator and ethylene synthon via a retro‐Diels–Alder reaction. Comprehensive DFT calculations were performed to account for the catalytic intermediates.