Nano-SiO2/hexamethylenetetramine promoted synthesis of pyrano[2,3-c] pyrazoles under solventfree conditions

In this study, the nano-SiO2/hexamethylenetetramine as a new basic heterogeneous nanocatalyst was prepared and used for the synthesis of pyranopyrazole via the fourcomponent reaction. Various aldehydes, hydrazine hydrate, ethyl acetoacetate and malononitrile were reacted at room temperature under solventfree and grinding conditions. The morphology and structure of nanocatalyst were investigated by techniques such as FTIR spectroscopy, FESEM, TEM, XRD, CHNS elemental analyzer and TGA. The structure of pyranopyrazoles was determined by spectroscopic data of FTIR and NMR. The principal affairs of this procedure are easy workup, high yields, mild conditions and short reaction times.