One-Pot Sequential N-Heterocyclic Carbene/Rhodium(III) Catalysis: Synthesis of Fused Polycyclic Isocoumarins

A one-pot sequential N-heterocyclic carbene-rhodium (NHC-Rh) catalysis is described, demonstrating the compatibility of NHC and Rh catalysts. N-Heterocyclic carbene-catalyzed aerobic oxidation of benzaldehydes and subsequent rhodium(III)-catalyzed oxidative coupling/ annulation with multiple bonds enabled the formation of two C-O bonds and one C-C bond in a single pot. This operationally easy, one-pot protocol under air provides access to a diverse array of valuable fused polycyclic isocoumarins.