One-pot synthesis of 1,4-dihydropyridine derivatives using nanocomposite hydrogel as a catalyst

Dihydropyridine (DHP) derivatives contain a large family of medicinally important materials that have attracted much attentiondue to their various medicinal properties. In view of the biological, industrial and synthetic importance of 1,4-dihydropyridines,several methods for their synthesis have been reported. The classical Hantzsch condensation method for the synthesis of 1,4-dihydropyridines is one-pot condensation of aldehydes with ethyl acetoacetate, and ammonia using acetic acid at room temperatureor by refluxing in alcohols for a long time. This method involves harsh reaction conditions, long reaction times, and low yields ofproducts. Therefore, several alternate and more efficient methods have been developed for the synthesis of dihydropyridinederivatives using ionic liquid, Zeolite, polymers, and so on. Although most of these processes have distinct advantages, the use ofhigh temperatures, expensive metal precursors, environmentally harmful catalysts, harsh reaction conditions, long reaction timesand large quantity of volatile organic solvents limit the use of these methods. So in green point of view the search for the possibilityof performing multicomponent reactions under solvent-free conditions with recoverable catalysts for the synthesis of thesecompounds is an active ongoing research area and there is scope for further improvement toward milder reaction conditions andhigher yields. Nanocomposites have high surface-to-volume ratio and coordination sites compared to their bulk analogs, whichprovide a larger number of active sites per unit area. Recently, magnetic nanocomposites were used as an efficient catalyst in manyorganic reactions. Hence, we decided to green synthesis 1,4-dihydropyridine derivatives using magnetic nano-composite hydrogelbased on carboxymethylcellulose (MNCH-CMC) under solvent-free conditions. A green approach for efficient and rapid synthesisof biologically active substituted Hantzsch 1,4-dihydropyridine derivatives using MNCH-CMC as a recyclable catalyst undersolvent-free conditions was performed. The catalyst was characterized by FT-IR, and TEM analysis. Compared to the classicalreactions, this method consistently has the advantages of short reaction times, little catalyst loading, high yields, and reusability ofthe catalyst.

کلیدواژه ها:

Magnetic nano-composite hydrogel based on carboxymethylcellulose ، Heterogeneous catalyst ، Hantzsch reaction ، One-potsynthesis ، 1 ، 4-dihydropyridine