Alum catalyzed simple and efficient synthesis of Bis(indolyl)methanes by ultrasound approach

Abstract

Alum (KAl(SO4)2 12H2O) is an inexpensive, efficient, non-toxic and mild catalyst for the synthesis of bis(indolyl)methanes by the reaction of 1H-indole with various aldehydes/ketones under the influence of ultrasound irradiation in solvent-free condition. The remarkable advantages of this method are the simple experimental procedures, shorter reaction times, high yields of product and green aspects by avoiding toxic catalysts and solvents.