Magnetically recyclable Fe₃O₄@SiO₂@GPTMS/2-aminophenol-Cu(II) nanocatalyst for green one-pot synthesis of 2-amino-4H-benzo[b]pyrans via solvent-free grinding technique

چکیده مقاله

In response to the growing demand for sustainable catalysis in organic synthesis, this study introduces a novel, eco-friendly core-shell Fe₃O₄@SiO₂@GPTMS/2-aminophenol-Cu(II) magnetic nanocatalyst. The catalyst was synthesized via a straightforward procedure and thoroughly characterized using FT-IR, FE-SEM, TEM, EDX, TGA, VSM, XRD, and ICP techniques. TEM analysis confirmed a particle size distribution of 10–26 nm (average 31 nm), while TGA demonstrated excellent thermal stability, with 39.5% weight retention up to 800 °C. The nanocatalyst exhibited superior activity in the one-pot Knoevenagel–Michael Cyclocondensation of aromatic aldehydes, malononitrile, and dimedone under solvent-free, room-temperature mortar-pestle grinding conditions, yielding 2-amino-4H-benzo[b]pyran derivatives with excellent purity and yields (>90% in most cases). This method aligns with green chemistry principles through minimal waste, mild conditions, and low catalyst loading (1.3 mol%). Furthermore, its superparamagnetic properties facilitate easy magnetic recovery and reuse for at least five cycles with negligible loss in activity. This approach offers a versatile, efficient platform for heterocycle synthesis, emphasizing sustainability and recyclability. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.