H₅BW₁₂O₄₀as a green and efficient homogeneous but recyclable catalyst in the synthesis of 4<i>H</i>‐Pyrans<i>via</i>multicomponent reaction

Abstract

Keggin‐type heteropolyacid, H 5 BW 12 O 40 (BWA) with a higher negative charge and stronger Brønsted acidity comparing to Si and P derivatives was used as an efficient, green, and reusable catalyst in a three‐component reaction involving the cyclocondensation of various β‐dicarbonyl compounds, differently substituted aromatic aldehydes and malononitrile in EtOH/H 2 O for the facile, clean, and high yielding synthesis of 4 H ‐pyrans. All reactions were completed in short times and the products were obtained in good to excellent yields. The reaction medium could be recycled and reused several times without any loss of efficiency.