Magnetic resorcinol–formaldehyde supported isatin-Schiff-base/Fe as a green and reusable nanocatalyst for the synthesis of pyrano[2,3-d]pyrimidines

Herein, a novel magnetic resorcinol–formaldehyde-supported isatin-Schiff-base/Fe complex (Fe₃O₄@RF-ISB/Fe) is prepared and characterized and its catalytic performance is investigated in the synthesis of pyrano[2,3-d]pyrimidines. The Fe₃O₄@RF-ISB nanomaterial was prepared through the chemical immobilization of (3-aminopropyl)trimethoxysilane over the Fe₃O₄@RF composite, followed by treatment with isatin. The Fe₃O₄@RF-ISB was then reacted with FeCl₃·6H₂O to afford the Fe₃O₄@RF-ISB/Fe nanocatalyst. Characterization through FT-IR, EDX, PXRD, VSM, SEM and ICP techniques confirmed that the magnetite surface was successfully modified with RF/ISB-Fe while preserving its crystalline structure. The SEM image revealed spherical particles with an average size of 44 nm for the designed nanocomposite. Various aromatic aldehydes were used as substrates in the presence of 0.01 g of Fe₃O₄@RF-ISB/Fe to give the corresponding pyranopyrimidines in high yields (88–95%) within short reaction times (30–55 minutes) at RT. The designed magnetic catalyst maintained its activity for nine runs.