New 1,5-dicarbonyl compounds were prepared, as versatile precursors to pyridine derivatives, by a tandem Claisen-Schmidt condensation/ Michael addition reaction, that is condensation between 5-chloro-3-methyl-1-phenyl-1Hpyrazole- 4-carbaldehyde and acetophenones, and the formed adduct then reacts with a second molecule of acetophenone. The preparation of substituted pyridines was achieved using NH4OAc as nitrogen source under solvent-free microwave irradiation. Keywords: Chalcone, 1,5-dicarbonyl compounds, cyclocondensation, microwave, NH4OAc, pyridines, solvent-free procedure, heterocyclic, antifungal, antibacterial