KF-Al<sub>2</sub>O<sub>3</sub> as an Efficient and Recyclable Basic Catalyst for the Synthesis of 4<i>H</i>-Pyran-3-carboxylates and 5-Acetyl-4<i>H</i>-pyrans

Abstract

KF-Al2O3 as a recyclable basic catalyst for the three-component synthesis of 4H-pyran derivatives by the reaction of aldehydes, malononitrile and active methylene dicarbonyl compounds in ethanol at room temperature is described. The protocol is environmentally benign and offers rapid access to a wide array of 4H-pyran heterocycles in good to excellent yields.