Fe3O4 MNPs as a green catalyst for syntheses of functionalized [1,3]-oxazole and 1H-pyrrolo-[1,3]-oxazole derivatives and evaluation of their antioxidant activity.

In the present study, iron oxide magnetic nanoparticles (Fe3O4 MNPs) were synthesized in a green biosynthetic manner using aqueous extract of clover leaves. Fe3O4 MNPs were applied as a magnetically separable nanocatalyst for the green syntheses of functionalized [1,3]-oxazoles 1(a-e) and 1H-pyrrolo-[1,3]-oxazoles 4(a-i) as promising antioxidant compounds in excellent yields at 50 °C and room temperature, respectively. The antioxidant activities of the most stable compounds (1a, 1b, 4a, and 4b) were evaluated by both 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferric reduction activity potential assays. Compound 1b was shown a remarkable radical scavenging activity, and 4a was shown very good reducing activity relative to standards (BHT and TBHQ).