LAUSR

Abstract It was found that nano-SiO 2 –H 2 SO 4 was catalyzed by the three-component cyclocondensation of aryl/heteroaryl aldehydes, hydroxylamine hydrochloride, and β -ketoesters toward the synthesis of α , β -unsaturated isoxazol-5(4 H )-ones under green conditions. The reaction yielded the corresponding heterocycles at room temperature in relatively shorter reaction times. It merits mentioning that the mild conditions allow the synthesis of several α , β -unsaturated isoxazol-5(4 H )-ones using this method. In this study, some new derivatives of isoxazolones were also synthesized and characterized. It is efficient, clean, simple, safe, and ecologically friendly. This straightforward method is cost-effective and requires no preparation of reactants. The three-component annulation was performed without using energy sources, for example, heat, ultrasound wave, and microwave irradiation. Graphic abstract