Simple and Efficient Method for Synthesis of Bis(indolyl) Methanes with Cu(BF4)2·SiO2 Under Mild Conditions

A simple and efficient synthesis of bis(indolyl) methanes by the reaction of indoles with various carbonyl compounds in the presence of a catalytic amount of cupric fluoroborate [Cu(BF4)2·SiO2] afforded the corresponding bis(indolyl) methanes in excellent yields. The remarkable selectivity under mild and neutral conditions and commercially available, inexpensive catalyst are attractive features of this method.