Zirconium dioxide (ZrO2) as an efficient catalyst for the Synthesis of Tetrahydrobenzo[b]pyran drivatives

4H-pyran derivatives have useful pharmacological and biological properties such as, spasmolytic, anti-cancer, anti-coagulant, diuretic characteristics. 4H-Pyrans also occur in various natural products1, 2. Some of these derivatives have photochemical activities3. Various methods and catalysts have been reported for the preparation of 4H-pyrans such as TEBA4, KF-basic alumina under ultrasound irradiation5. In this work, we have used zirconium dioxide (ZrO2) as an efficient, commercially available, heterogeneous and recyclable catalyst for the preparation of 4H-pyrans via the One-Pot multi-component condensation of dimedone, aryl aldehydes, and malononitrile under solvent-free conditions (Figure 1).