Efficient synthesis of new pyrano[3,2-b]pyran derivatives via Fe3O4@SiO2-IL-Fc catalyzed three-component reaction

Ferrocene-containing ionic liquid supported on silica-coated Fe3O4 magnetic nanoparticles (nano Fe3O4@SiO2-IL-Fc), a novel heterogeneous nanocatalyst, was synthesized. The structure of the catalyst was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction patterns (XRD), energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FE-SEM). The novel nanomagnetic catalyst was used in the one-pot synthesis of pyrano[3,2-b]pyran derivatives by the three-component reaction of various aldehydes, malononitrile and kojic acid or chlorokojic acid at room temperature under ultrasonic irradiation. This new method has many advantages such as simplicity, short reaction times, high yields, easy workup and easy purification. Also, the nanocatalyst can be separated on an external magnet and reused for at least six consecutive runs without any significant loss of its catalytic activity.