Synthesis of Tetrahydrobenzo[b]pyran and Pyrano[2, 3-d]pyrimidinone Derivatives Using Fe₃O₄@Ph-PMO-NaHSO₄ as a New Magnetically Separable Nanocatalyst.

Immobilized NaHSO₄ on core/shell phenylene bridged periodic mesoporous organosilica magnetic nanoparticles (Fe₃O₄@Ph-PMO-NaHSO₄) as a new acidic magnetically separable nanocatalyst was successfully prepared in three steps: (i) preparation of Fe₃O₄ nanoparticles by a precipitation method, (ii) synthesis of an organic-inorganic periodic mesoporous organosilica structure with phenyl groups on the surface of Fe₃O₄ magnetic nanoparticles (MNPs) and (iii) finally adsorption of NaHSO₄ on periodic mesoporous organosilica (PMO) network. The prepared organic-inorganic magnetic reagent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption-desorption and energy-dispersive X-ray (EDX) techniques. Finally, it was used as a reusable and new catalyst to promote the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-d]pyrimidinone derivatives as important biologically active compounds. Eco-friendly protocol, high yields, short reaction times and easy and quick isolation of the products are the main advantages of this procedure.