Magnetic core–shell titanium dioxide nanoparticles as an efficient catalyst for domino Knoevenagel–Michael-cyclocondensation reaction of malononitrile, various aldehydes and dimedone

Abstract

Magnetic core–shell titanium dioxide nanoparticles (Fe₃O₄@SiO₂@TiO₂) were efficiently used for the preparation of tetrahydrobenzo[b]pyran derivatives via a one-pot three component condensation reaction of various aldehydes, dimedone and malononitrile at 100 °C under solvent-free conditions. The catalyst was synthesized and characterized by several techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX).