Silica Ammonium Acetate as an Efficient and Recyclable Heterogeneous Catalyst for Synthesis of 4H-pyran Derivatives under Ultrasound Irradiation at Ambient Conditions

A simple, versatile and efficient method has been developed for the synthesis of 4H-pyran derivatives 4a-k via a three-component cyclocondensation of aldehydes, malononitrile and ethyl acetoacetate under heterogeneous conditions using silica supported ammonium acetate as the recyclable catalyst, promoted by ultrasound irradiation. The present method offers several advantages such as the products are obtained in excellent yields and are in a state of high purity, non hazardous reaction conditions as well as short reaction times.