H5BW12O40 as a green and efficient homogeneous but recyclable catalyst in the synthesis of 4H‐Pyrans via multicomponent reaction

Keggin‐type heteropolyacid, H₅BW₁₂O₄₀ (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/H₂O for the facile, clean, and high yielding synthesis of 4H‐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.