Fe3O4-MNPs@MMT-K10: a reusable catalyst for synthesis of propargyl 4-aryl-4H-pyran-3-carboxyles via one-pot three-component reaction under microwave-assisted solvent-free conditions

In this work, we prepared successfully a recoverable heterogeneous magnetic nano-catalyst Fe3O4-MNPs@MMT-K10. This catalyst was characterized by energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Its catalytic behavior was efficiently used for the synthesis of highly substituted pyran/chromene derivatives (4a-m and 6a-m, respectively) containing propargyl unit through a one-pot three-component condensation of propargyl acetoacetate/3-propargyloxyphenol, malononitrile, and arylaldehydes under microwave-assisted solvent-free conditions. Some important features of this catalyst were found, including short reaction times, excellent yields, lower loading of the catalyst, easy work-up, and recyclability. It was showed that the obtained catalyst exhibited the catalytic stability and the reusability for a minimum of six times without any noticeable decrease in its catalytic activity. Also, thirteen novel substituted propargyl 6-amino-4-aryl-5-cyano-2-methyl-4H-pyran-3-carboxylates 4a-m were synthesized by three-component reaction of propargyl acetoacetate with malononitrile and benzaldehydes using this catalyst. Their structure was determined by measuring the spectral properties as well as by single-crystal X-ray crystallography of a representative compound 4i. 1-Alkyne was one of the two substances needed for click chemistry, along with organic azides and propargyl esters as well as ethers were synthesized for this purpose. Graphic Abstract