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

Abstract

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.