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… Click to show full 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.
               
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