Co(NO3)2.6H2O: A Mild, Efficient and Novel Catalyst for the One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives

Recently, tetrahydrobenzo[b]pyran derivatives are known as an important class of heterocyclicscaffolds in the field of drugs and pharmaceuticals [1]. These compounds exhibit significantbiological properties such as antibacterial, antitumor, anti-allergic, antibiotic, hypolipidemicand immunomodulating activates [1-3]. In this paper, we want to report a one pot reactionfor the synthesis of tetrahydrobenzo[b]pyran derivatives using dimedone (1 mmol),malonitrile (1 mmol), aldehyde (1 mmol) in the presence of a catalytic amount (20 mol%) ofCo(NO₃)₂.6H2O in EtOH: H2O at 70 °C. The advantages of this method are simple work-up,short reaction time, high yields and using eco-friendly metal.