Gold-catalyzed oxidative couplings of two indoles with one aryldiazo cyanide under oxidant-free conditions

Gold-catalyzed oxidative couplings of two indoles and one α-cyano gold carbene to form bis(indolyl)methane derivatives are described. Two different indoles are compatible with these reactions to provide reasonable yields. A plausible mechanism is postulated to rationalize the experimental data including product distributions, D O labeling, and the significant effects of gold catalysts and cyano groups.