Chitosan: An efficient biomacromolecule support for synergic catalyzing of Hantzsch esters by CuSO4.

The synergic effect of the chitosan biomacromolecule support for catalyzing of Hantzsch esters formation by CuSO4 has been demonstrated for one-pot and efficient pseudo-four-component reaction to afford a wide range of 1,4-dihydropyridine (DHP) or polyhydroquinoline (PHQ) derivatives. The desired products were simply prepared from different aldehydes, β-dicarbonyls and ammonium acetate in the presence of a low loading of chitosan supported copper(II) sulfate (CSCS) in EtOH under reflux conditions. The biodegradable CSCS catalyst was characterized by field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy analysis (EDX) methods as well as coupled plasma-atomic emission (ICP-AE) and FT-IR spectroscopy. The CSCS catalyst is recyclable and reused four times without significant loss of its activity.