NiZnFe2O4: an eco-compatible and magnetically separable catalyst for multicomponent synthesis of 2-amino-4H-chromenes

The magnetically separable heterogeneous nickel–zinc ferrite (NiZnFe 2 O 4 ) catalyst was synthesized and used for the first time as an environmentally friendly reusable catalyst for the synthesis of 2-amino-4 H -chromene derivatives via a one-pot, three-component condensation reaction of various salicylaldehydes and malononitrile or ethyl cyanoacetate with nitromethane or nitroethane in ethanol at room temperature. There have been no reports of nickel zinc ferrite being used as a catalyst. The catalyst was specified by using several techniques, including DSC–TGA, FT-IR, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), BET, and scanning electron microscope (SEM). The present protocol suggests some benefits, which include green reaction conditions, simple reaction work-up, short reaction time, excellent product yields, chromatography-free purification, and high efficiency of the heterogeneous catalyst. More importantly, this catalyst was recovered from the reaction mixture using a simple external magnet, and it was reused successively at least seven times without any significant loss of catalytic activity. Graphical abstract