Synthesis of bis(indolyl)methanes using molten N-butylpyridinium bromide

A simple and rapid protocol has been developed for the synthesis of bis(indolyl)methane compounds in excellent yields using molten N-butyl-pyridinium bromide as a solvent and a working catalyst for the reaction. Synthesis of bis(indolyl)methane compounds were accomplished at moderate experimental conditions of temperature and ambient pressure, also involving an electrophilic substitution reaction of indoles with several aromatic aldehydes. The derivatives were confirmed with mass and other usual spectroscopic techniques. A discussion on plausible mechanism for the reaction is also presented.