Ferrocene‐tagged ionic liquid stabilized on silica‐coated magnetic nanoparticles: Efficient catalyst for the synthesis of 2‐amino‐3‐cyano‐4H‐pyran derivatives under solvent‐free conditions

An advanced novel magnetic ionic liquid based on imidazolium tagged with ferrocene, a supported ionic liquid, is introduced as a recyclable heterogeneous catalyst. Catalytic activity of the novel nanocatalyst was investigated in one-pot three-component reactions of various aldehydes, malononitrile and 2-naphthol for the facile synthesis of 2-amino-3-cyano-4H-pyran derivatives under solvent-free conditions without additional co-catalyst or additive in air. For this purpose, we firstly synthesized and investigated 1-(4-ferrocenylbutyl)-3-methylimidazolium acetate, [FcBuMeIm][OAc], as a novel basic ferrocene-tagged ionic liquid. This ferrocene-tagged ionic liquid was then linked to silica-coated nano-Fe3O4 to afford a novel heterogeneous magnetic nanocatalyst, namely [Fe3O4@SiO2@Im-Fc][OAc]. The synthesized novel catalyst was characterized using 1H NMR, 13C NMR, Fourier transform infrared and energy-dispersive X-ray spectroscopies, X-ray diffraction, and transmission and field emission scanning electron microscopies. Combination of some unique characteristics of ferrocene and the supported ionic liquid developed the catalytic activity in a simple, efficient, green and eco-friendly protocol. The catalyst could be reused several times without loss of activity.