Highly efficient solvent-free synthesis of novel pyranyl pyridine derivatives via β-enaminones using ZnO nanoparticles

Highly efficient ZnO nanoparticle catalyzed one-pot solvent-free synthesis of novel pyridine derivatives by three-component reaction of β-enaminones, different active methylene compounds, and ammonium acetate via Michael addition, cyclodehydration, and elimination sequence is reported. The catalyst was recyclable up to six catalytic cycles without a significant loss in the catalytic activity. This new protocol has the advantages of environmental friendliness, higher yields, solvent-free, low loading of catalyst, shorter reaction times, and convenient operation procedure. ZnO nanoparticles were characterized by XRD, SEM, and TEM analyses.