Nano-Ferrite ZnFe2O4 as Efficient and Re-Usable Catalyst for the Synthesis of 4H-Chromenes and 4H-Pyrano[2,3-c] pyrazoles

Nano-magnetic ferrite ZnFe2O4 among other magnetic nanoparticles include Fe2O3, Fe3O4, Ni(0.7)Zn(0.3)Fe2O4 and Mn(0.7)Zn(0.3)Fe2O4 was explored as an efficient catalyst for the synthesis of various 4H-Chromenes and 4H-Pyrano[2,3-c]pyrazoles in EtOH/H2O (2:1) via an easy and green procedure. The desired products were obtained in high yields via a three-component reaction between aromatic aldehydes with malononitrile and 5,5-dimethyl-cyclohexane-1,3-dione or 3-methyl-1-phenyl-2-pyrazolin-5-one at room temperature. The structure of this catalyst was fully characterized via Fourier transform infrared spectroscopy, XRD, SEM, TEM, EDAX, and VSM. The employed nanocatalyst was easily recovered using a magnetic field and reused ten times (in subsequent runs) without observation a significant decrease in activity.