One-pot synthesis of 3,4-dihydropyrimidin-2(1)-ones catalyzed by SOH@imineZCMNPs as a novel, efficient and reusable acidic nanocatalyst under solvent-free conditions.

The synthesis of 3,4-dihydropyrimidin-2(1)-one derivatives was accomplished efficiently a three-component reaction between ethyl acetoacetate, various types of aldehydes, and urea in the presence of 10 mg SOH@imineZCMNPs as a novel, environment friendly, and reusable heterogeneous magnetic nanocatalyst under solvent-free conditions at 90 °C. The desired products were obtained with high quantitative yields. The catalyst was separated by simple isolation from the reaction mixture using a permanent magnet and reused several times without any significant loss of catalytic activity. The synthesized catalyst was fully characterized through various techniques including thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and the Hammett acidity test. This methodology tolerates most substrates and has the salient features of green reaction conditions, lower catalyst loading, high quantitative yields, low cost, the absence of solvents, and easy isolation and reusability of the catalyst.