A novel Cu(II) complex immobilized on ZrFe۲O۴ magnetic nanoparticlescatalyzed synthesis of pyranopyrazols

Heterogeneous catalysis plays a crucial role in many chemical processes, including advancedorganic preparations and the design and synthesis of new organic moieties [۱]. Efficient andsustainable catalysts are vital to ecological and fiscal viability [۲]. This is why greenmulticomponent reaction (MCR) approaches have gained prominence. Owing to a broad range ofpharmacological applications, pyranopyrazole syntheses (through the one-pot strategy,employing sustainable heterogeneous catalysts) have received immense attention [۳]. Here, thesynthesis of efficient heterogenous catalysts for the environmentally friendly and economicsynthesis of pyranopyrazoles was reported via multicomponent reactions between hydrazinehydrate, ethyl acetoacetate, malononitrile, and aromatic aldehydes. A nanomagnetic Cu(II)complex was synthesized through the immobilization of tryptophan on the ZrFe۲O۴ surface andits complexation with Cu salt. It was characterized by FTIR, XRD, EDX, Map, SEM, TEM,VSM, and BET/BJH methods. The structures of pyranopyrazol compounds were fully confirmedvia IR, ۱H NMR, and ۱۳C NMR spectroscopic studies. High yields of products, the use of a greensolvent, the easy work-up procedure, the short reaction times, and the easily separable catalystare the main advantages of this protocol.

Keywords:

ZrFe۲O۴ , tryptophan-Cu(II) complex , pyranopyrazoles , Lewis acid catalyst