Green Synthesis of Arylideneisoxazol-5-Ones Catalyzed by Silicon Dioxide Nanoparticles

4-Arylideneisoxazol-5(4H)-ones were obtained via a simple and efficient one-pot, three-component cyclocondensation of diverse aldehydes with hydroxylamine hydrochloride and β-keto esters in water. This one-pot heterocyclization has been performed in the presence of catalytic amounts of silicon dioxide nanoparticles (SiO₂ NPs) at room temperature. This approach is economical for the synthesis of potentially bioactive 4-arylideneisoxazol-5(4H)-one derivatives. The products were formed in 86–94% isolated reaction yields using 5 mol% nanocatalyst. The heterocyclization reactions were completed at room temperature under aqueous conditions. The significant features of the present procedure are uncomplicated product isolation, purification without chromatographic methods, great biocompatibility of SiO₂ NPs, straightforward reaction conditions, easy workup, environmentally friendly, readily available starting materials, reusability of the catalyst, as well as inexpensive and green reaction medium.