Paal knorr reaction for novel pyrrolo[2,3-d]pyrimidines

Ultrasound-assisted synthesis of 2,5-dimethyl-N-substituted pyrroles catalyzed by uranyl nitrate hexahydrate

An efficient synthesis of different novel 2,5-dimethyl-N-substituted pyrrole derivatives by the Paal-Knorr condensation has been accomplished using uranyl nitrate hexahydrate as catalyst under soft conditions and ultrasonic irradiation. The synthesized compounds were confirmed through spectral characterization using IR, (1)H NMR, (13)C NMR and mass spectra.

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.