Ultrasound-assisted synthesis of pyrroles catalyzed by zirconium chloride under solvent-free conditions

A straightforward synthesis of substituted pyrroles using zirconium chloride-catalyzed modified Paal–Knorr method has been accomplished under ultrasound irradiation. Compared to known methods, this new method provides as easy access to various substituted pyrroles in good to excellent yields with short reaction times.