چكيده فارسي :
Multi-component reactions (MCRs) achieve significant role in combinatorial chemistry due to the ability to prepare target compounds with more efficiency and atomic economy by the reaction of three or more compounds together in a single step. Also, MCRs increase simplicity and synthetic efficiency on the conventional organic synthesis [1,2]. The synthesis of tetrahydrobenzo[b]pyran derivatives is important due to their significant anti-coagulant, diuretic, spasmolytic, anticancer, and anti-anaphylactic properties. 2-amino-4H-pyran derivatives can be widely used as photoactive materials. Additionally, substituted 4H-pyrans are observed as units in the structure of some natural products [3,4].
In the present study, for the first time, magnetically NiFe2O4@CuO nanocomposite was synthesized using tragacanth gel as a green capping agent and biotemplate by the sol-gel method. NiFe2O4@CuO magnetic nanocomposite was investigated using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) vibrating sample magnetometer (VSM) and Transmission electron microscopy (TEM). XRD results show that NiFe2O4@CuO nanocomposite corresponds to the monoclinic of CuO and the spinel cubic structure of NiFe2O4. Thereupon, a green and efficient method is described for the solvent free synthesis of tetrahydrobenzo[b]pyran derivatives through one-pot three-component condensation of dimedone, an aryl aldehyde, and malononitrile in the presence of NiFe2O4@CuO nanocomposite as high-performance magnetic catalyst under microwave irradiation (scheme 1). Simple work-up, mild reaction conditions, short reaction times, use of an economically convenient catalyst, and excellent product yields are the advantageous features of this method. The catalyst could easily be recycled and reused five times without noticeable decrease in catalytic activity.
