Sulfated polyborate: An efficient and reusable catalyst for one pot synthesis of Hantzsch 1,4-dihydropyridines derivatives using ammonium carbonate under solvent free conditions

A simple and efficient method for the synthesis of four-component 1,4-dihydropyridines of various aldehydes, β-ketoesters and ammonium carbonate catalyzed by sulfated polyborate with high yields under a solvent free condition at 90 °C is described. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup, recyclability of catalyst and ability to tolerate a variety of functional groups which gives economical as well as ecological rewards.