co3o4 nanoparticles as a robust and recoverable catalyst for one-pot synthesis of polyhydroquinolines and tetrahydrobenzopyrans

this study introduces a green and efficient method for preparation of biologically-active substituted 4h-pyrans using the one-pot three-component reaction of aromatic aldehydes, dimedone and malononitrile in the presence of cobalt oxide nanoparticles. co3o4 nanoparticles were used as an efficient catalyst for the synthesis of polyhydroquinoline derivatives by the reaction of aromatic aldehydes, ethyl acetoacetate, dimedone and ammonium acetate. the preparation and use of co3o4 as a powerful and reusable nanocatalyst under solvent-free conditions is described. the catalyst was characterized by spectral techniques including xrd, fe-sem, ft-ir, vsm, edx and tem analysis. this method offers the advantages of high yield, short reaction time, comfortable work-up and reusability of the catalyst.