Green and Biogenic Synthesis of Cerium Oxide (CeO2) Nanoparticles: Heterogeneous Catalytic Synthesis of Isoxazol-5(4H)-one Derivatives and Assessment of Their Antibacterial Activity

The development of eco-friendly, sustainable, and efficient catalytic systems has become a highly attractive area of research for promoting heterogeneous organic reactions. In this study, we report the use of cerium oxide nanoparticles (CeO₂ NPs) as a heterogeneous catalyst for the one-pot synthesis of isoxazol-5(4H)-one derivatives. The CeO₂ NPs were synthesized via an environmentally benign method using an extract from Holy Basil (Ocimum sanctum), offering a green, sustainable, and cost-effective approach. This green synthesis not only minimizes the use of hazardous chemicals but also enhances the physiochemical properties of the CeO₂ NPs, including their catalytic performance. The catalytic activity of the synthesized nanoparticles was evaluated through reactions involving a variety of aldehydes, hydroxylamine hydrochloride, and β-dicarbonyl compounds. A wide range of isoxazol-5(4H)-one derivatives was obtained with excellent yields and high purity under mild conditions. Furthermore, the reusability of the CeO₂ NPs was thoroughly investigated, demonstrating minimal loss of activity over multiple reaction cycles. This study highlights a promising and sustainable method for synthesizing valuable heterocyclic compounds using green nanotechnology, thereby contributing significantly to the advancement of environmentally responsible practices in synthetic organic chemistry. Moreover, the antibacterial properties of the isoxazol-5(4H)-one derivatives further emphasize the significance of the green-synthesized CeO₂ NPs.