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The four-component Hantzsch condensation reaction of dimedone, ethyl acetoacetate, ammonium acetate, and various aromatic and aliphatic aldehydes in the presence of catalytic amount of a magnetic nanoparticle-supported tribromide, as a green catalyst, under solvent‐free conditions at 80 °C affords functionalized 5-oxo-hexahydroquinolines in good to excellent yields. The magnetic Fe3O4-SiO2-(CH2)3N+Me3Br3–, was characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD)spectroscopy, transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The method offers several advantages including high yields, short reaction time, simple work-up procedure and catalyst reusability for several runs. The catalyst could be readily separated by using a magnetic force and reused six times without any significant loss of catalytic activity.

Authors: Azita Farrokhi, Issa Yavari, Keivan Ghodrati

Functionalized magnetic core–shell nanoparticles [Fe3O4/SiO2/(CH2)3N+Me3Br3−] are prepared by coprecipitation method, characterized by transmission electron microscopy, FT-IR, X-ray diffraction, and vibrating sample magnetometer. The catalytic activity of these nanoparticles was tested in the syntheses of imidazole, benzothiazole, and perimidine derivatives, under solvent-free conditions. The catalyst was readily recycled by the use of an external magnetic field and could be reused five times without significant loss of activity or mass.

Authors: Azita Farrokhi , Keivan Ghodrati , Issa Yavari