Cerium ammonium nitrate (CAN)-catalyzed four-component one-pot synthesis of multi-substituted pyrano[2,3-c] pyrazoles under ultrasound irradiation.

A convenient and efficient synthesis of multi-substituted dihydropyrano[2,3-c]pyrazole derivatives is reported. The four-component reaction of 4-hydrazinobenzoic acid, β-keto esters, aromatic aldehydes, and malononitrile using 10 mol% CAN catalyst in water under ultrasound irradiation produced the target compounds in good-to-excellent yields. This method has advantages over conventional methods in being economic, non-toxic, and environmentally compatible due to its use of efficient and eco-friendly CAN catalyst and water solvent.