Bio-Fe₃O₄ Magnetic Nanoparticles Promoted Green Synthesis of thioxo- 1,3-Oxazole Derivatives: Study of Antimicrobial...

In this work, 1,3-oxazoles were generated using the multicomponent reaction of α-bromo ketones, alkyl (aryl) isothiocyanates, sodium hydride and Fe3O4 MNPs in the water at room temperature in good yields. The nanoparticles generated via the biosynthesis method have potential value in different purposes, such as organic synthesis.

To study the antioxidant ability of some synthesized thioxo-1,3-oxazoles, diphenyl-picrylhydrazine (DPPH) radical trapping and power of ferric reduction testes are employed. Among the studied thioxo-1,3-oxazoles, compound 4b have good power for radical trapping and reduction activity than the standard antioxidants such as BHT and TBHQ. In addition, the antimicrobial activity of some thioxo-1,3-oxazoles was studied, employing the disk diffusion test on Gram-positive bacteria and Gram-negative bacteria. The results of the disk diffusion test showed that compounds 4a, 4b, 4d and 4f prevented bacterial growth.

Without employing catalyst, these reactions have low yield and busy mixture. The synthesis of compound 4a as sample reaction has a similar yield in the presence of ZnO-NPs and Fe3O4 MNPs (entry 20 and entry 30), but the removal of catalyst from the mixture of reaction after the completion of the reaction is comfortable in the presence of Fe3O4 MNPs. Structures of compound 4a-4i are confirmed by IR, 1H NMR and 13C NMR mass spectra.

The reaction of α-bromo ketones, isothiocyanate and sodium hydride in the presence of the catalytic amount of Fe₃O₄ MNPs in water generates 1,3-oxazole derivatives in good yields. Some of the advantages of performing these reactions with the present procedure are to carry out these reactions in water as a green solvent and simple removal of catalyst.