(Nh4)(2)S2o8-Promoted Direct C-C Coupling Of Indoles With Quinones/Hydroquinones Without Catalyst

An atom-economical and environmentally benign approach for the synthesis of 3-indolylquinones was achieved successfully via direct oxidative C-C coupling of quinones/hydroquinones with indoles using (NH4)(2)S2O8 in dichloroethane at 80 degrees C. The efficiency of this catalytic approach was established by a broad scope of substrates involving quinones and hydroquinones to give high yields (61-93%) of 3-indolylquinones. The present protocol is simple, practical, and show good functional group tolerance. In addition, the obtained 3-indolylnaphthoquinones were conducted to further transformation to synthesize 2-amino-3-indolylnaphthoquinone and polycyclic N-heterocycles, respectively.