Efficient synthesis of 4H-pyran derivatives using a polymeric catalyst based on PVP

A one-pot efficient method for the synthesis of 4H-pyran derivatives has been developed through a multi-component reaction of aldehydes, malononitrile, and 1,3-cyclic diketones using poly(vinylpyrrolidonium) hydrogen sulfate ([PVPH]HSO4) as a heterogeneous and reusable catalyst. The synthesized polymeric catalyst has fully been characterized by Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis, Hammett acidity (H-0), and pH analysis, which expose of the polymeric catalyst. This procedure has the advantages of operational simplicity, mild conditions, easy work-up, short reaction times, high yields of the products, and reusability of the catalyst.