Molecular sieves: an efficient and reusable catalyst for multi-component synthesis of dihydropyrano[2,3-C]pyrazole derivatives

An efficient synthesis of dihydropyrano[2,3-C]pyrazole derivatives catalyzed by molecular sieves in ethanol under reflux and ultrasound irradiation has been described. The efficiency of catalyst has been compared with other aluminates and silicate based catalyst in order to optimize the best catalyst for the said organic transformation. This protocol is very useful due to easy recovery of catalyst and its reusability, short reaction time, excellent yields, and avoidance of environmentally hazardous solvents.