An eco-friendly procedure for the efficient synthesis of bis(indolyl)methanes in aqueous media

A new, convenient and high yielding procedure for the preparation of bis(indolyl)methanes in water by electrophilic substitution reaction of indoles with different carbonyl compounds in the presence of a catalytic amount of [Cu(3,4-tmtppa)](MeSO4)4 (1 mol%) as a highly stable and reusable catalyst is described. This procedure has also been applied successfully for the preparation of bis(pyrazole-5-ols) and dipyrromethanes.