Fe₃O₄@nano-almond shell@OSi(CH₂)₃/DABCO: a novel magnetic nanocatalyst for the synthesis of chromenes

In this work, we report the synthesis and characterization of Fe₃O₄@nano-almond shell@OSi(CH₂)₃/DABCO as a novel magnetic natural-based basic nanocatalyst. The characterization of this catalyst was achieved using different spectroscopy and microscopy techniques, such as Fourier-transform infrared spectroscopy, X-ray diffractometry, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and mapping, vibrating-sample magnetometry, Brunauer-Emmett-Teller measurements, and thermogravimetric analysis. This catalyst was used for the one-pot synthesis of 2-amino-4H-benzo[f]chromenes-3-carbonitrile from the multicomponent reaction of aldehyde and malononitrile with α-naphthol or β-naphthol under solvent-free conditions at 90 °C. The yields of the obtained chromenes are 80-98%. The attractive features of this process are its easy work-up, mild reaction conditions, reusability of the catalyst, short reaction times and excellent yields.