Ultrasound-assisted synthesis of tetrahydrobenzo[b]pyran derivatives catalyzed by cobalt ferrite magnetic nanoparticles

The synthesis of tetrahydrobenzo[b]pyran derivatives is important because of their wide range of applications. These molecules are commonly employed in many felds such as anticoagulant, anticancer, spasmolytic, antibacterial, anti-anaphylactic activity, and diuretic [1,2]. Sonochemical synthesis is a facile, rapid, powerful and environmentally friendly technique, which has recently been applied to the synthesis of organic compounds. Ultrasonic irradiation formed bubbles, and their collapse generated localized hot spots with very short life-times and extremely high temperatures and pressures (up to 5000 °C and 2000 atm). An ultrasound approach is an important technique with prominent features including increased reaction rates, high yields, easier manipulation, mild reaction conditions, and waste minimization compared with traditional methods. Ultrasound is a more convenient method for green and sustainable synthetic processes [3,4]. In the present study, we have reported an efficient and convenient approach to the green synthesis of tetrahydrobenzo[b]pyrans using cobalt ferrite magnetic nanoparticles as the catalyst under ultrasound irradiation. This reaction was carried out through a three-component condensation reaction of malononitrile, dimedone and aldehyde in the presence of cobalt ferrite magnetic nanoparticles as a catalyst in water under ultrasound irradiation. This method provides several advantages such as environment friendliness, high yields and simple work-up procedure. Also, this catalyst can be easily separated from the reaction and recycled six times without activity loss