Ir(III)-catalyzed quadruple C-H activation of N -arylimidazolium and diaryliodonium salts: facile access to polysubstituted imidazo[1,2- f ]phenanthridiniums.

Herein, N-heterocyclic carbene-directed Ir(III)-catalyzed cascade C-H arylation/annulation of N -arylimidazolium with diaryliodonium salts has been accomplished for the first time via a quadruple C-H activation strategy to construct imidazo[1,2- f ]phenanthridinium structures. This protocol overcomes the compatibility of three kinds of different C-H activations with high catalytic efficiency, which allows ortho -unhindered N -arylimidazoliums to undergo a diarylation/annulation reaction, affording a variety of polysubstituted imidazo[1,2- f ]phenanthridiniums. Neutral imidazo[1,2- f ]phenanthridines are also prepared via a demethylation reaction of imidazo[1,2- f ]phenanthridiniums.