β-cyclodextrin-polyurethane polymer: A neutral and eco-friendly heterogeneous catalyst for the one-pot synthesis of 1,4-dihydropyridine and polyhydroquinolien derivatives via Hantzsch reaction under solvent-free conditions

Abstract

An efficient synthesis of 1,4-dihydropyridine & polyhydroquinolien derivatives using b-Cyclodextrin-polyurethane polymer (β-CDPU) as a stationary microvessel and neutral heterogeneous catalyst via a four component coupling of aldehydes, β-ketoester (2 mol) and ammonium acetate under solvent-free conditions is described. Compared with the classical Hantzsch reaction, this new method has the advantages of good yield, short reaction time and methodological simplicity. β-CDPU was proved to be an efficient heterogeneous catalyst which could be easily handled and removed from the reaction mixture by simple filtration, and also recovered and reused without loss of reactivity.

Keywords

• β-Cyclodextrin-polyurethane polymer
• 1,4-dihydropyridine and polyhydroquinolien derivatives
• heterogeneous catalyst
• four component coupling
• solvent