A Simple, Green and One-pot Four-component Synthesis of Polycyclic Dihydropyridine Derivatives

1,4-Dihydropyridines (1,4-DHPs) are important class of compounds in the field of drugs and pharmaceuticals [1]. The DHP moiety is common to numerous bioactive compounds. Recently, several modifications for this classical method have been reported for the facile and efficient synthesis of important dihydropyridine derivatives [2].Improvements in such syntheses have been sought continuously. Melamine-formaldehyderesin supported H+[MFRH] works under heterogeneous conditions. It is an inexpensive and non-hazardous solid acid catalyst. It can easily be handled and removed from the reaction mixtures by simple filteration [3]. In this communication, we describe a simple but effective modification of the Hantzschreaction that produces high yields of the desired dihydropyridines while preserving the original One-Pot strategy. The reaction of dimedone, barbitoric acid, aromatic aldehydes, and ammonium acetate in the presence of [MFRH] as a mild acid catalyst resulted in the formation of polycyclicdihydropyrimidinones (Figure 1) In conclusion, the present method demonstrates an operationally simple and clean procedure for the synthesis of polycyclic dihydropyridines using a catalytic amount of melamine-formaldehyderesin supported H+. In addition, low cost, recyclability, low toxicity, high acidity andmoisture compatibility of the catalyst, excellent yields of products within short reaction time make this methodology a valid contribution to the existing processes in the field of 1,4-Dihydropyridine synthesis..