Expeditious green synthesis of 3,4-disubstituted isoxazole-5(4<Emphasis Type="Italic">H</Emphasis>)-ones catalyzed by nano-MgO

In this work, it was found that magnesium oxide nanoparticles (nano-MgO) catalyzed one-pot three-component reaction of hydroxylamine hydrochloride with aryl aldehydes (or heteroaryl aldehydes) and β-oxoesters to synthesize some biologically active isoxazole-5(4H)-one-based heterocycles. The reactions were completed using 3 mol% catalyst loading in aqueous medium at room temperature. Nano-MgO was synthesized by precipitation and hydrothermal treatment of aqueous salt solution. The structure of the nano-MgO was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The presented environmentally friendly heterocyclization offers some interesting merits, including safety, high product yield, mild conditions, low cost, minimal waste, good atom efficiency, catalyst recoverable, energy efficiency, avoidance of hazardous organic solvents, and easy workup.