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

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.