Tandem Rh(III)-Catalyzed C-H Heteroarylation of Indolyl Ketones and Cu(II)-Promoted Intramolecular Cyclization: One-Pot Access to Blue-Emitting Phenanthrone-Type Polyheterocycles.

Disclosed herein is a highly efficient one-pot synthetic strategy to phenanthrone-type polyheterocycles via tandem rhodium(III)-catalyzed ortho-C-H heteroarylation of indolyl ketones and copper(II)-promoted intramolecular cyclization. This protocol enables a library of blue-emitting fluorophores with high quantum yields and narrow full widths at half-maximum to be rapidly built from readily available substrates, among of which 6,6,7,9,12-pentamethyl-6,12-dihydro-5 H-benzofuro[2,3- a]carbazol-5-one (4a) exhibits pure blue emission with Commission Internationale de I'Eclairage coordinates of (0.15, 0.09) and a high quantum yield of 85% in CHCl solution.