MgO-MgAl2O4: An efficient catalyst for multicomponent synthesis of substituted 4H-pyran

Abstract

The 4H-pyran compounds are an important class of heterocyclic compounds due to their diverse biological and pharmaceutical properties. Moreover, 4H-pyran is a crucial structural component commonly encountered in the pharmaceutical industry. Thus, it has recently gained significant attention from industry researchers and academic organizations. Herein, we report an efficient and eco-friendly one-pot strategy to synthesize bioactive compounds containing 4H-pyran motifs via a multicomponent reaction. This reaction occurs by reacting equimolar amounts of ethyl acetoacetate, malononitrile, and substituted aldehyde under mild conditions in the presence of a solid catalyst, MgO-MgAl2O4. This latter, was obtained by heat treatment, at 800°C, of a layered double hydroxide with the metal cation ratio of Mg2+/Al3+ = 3:1, and it was characterized by some techniques including XRD, TG-DTA, FT-IR and N2 adsorption-desorption. Therefore, bioactive compounds containing the pyran unit may possess intriguing biological properties. The synthetic protocol offers advantages such as a simple procedure, good to excellent yields, and easy catalyst separation from the reaction mixture. Substituted 4H-pyran derivatives were prepared by the condensation reaction of substituted aldehydes, ethyl acetoacetate and malononitrile using MgO-MgAl2O4 catalyst under mild conditions. This study aims to develop an efficient methodology for synthesizing 4H-pyran heterocyclic compounds that have potential applications in biological sciences. The study utilizes MgO-MgAl2O4 as a highly effective heterogeneous catalyst. The present research details the synthesis of 4H-pyran bioactive compounds using sustainable reaction conditions, which resulted in high yields and facilitated the easy separation of the catalyst from the reaction mixture. In summary, the MgO-MgAl2O4 spinel nanostructure has been successfully prepared and fully characterized by using different physicochemical techniques such as XRD, TG-DTA, FT-IR and N2 adsorption-desorption. Afterwards, its catalytic activity was investigated through the one-pot condensation of aryl aldehyde, malononitrile and ethyl acetoacetate. Moreover, it exhibits good catalytic activity for the synthesis of 4H-pyran derivatives under green conditions. These latter have many benefits, such as simple procedure, good to excellent yields and easy separation of the catalyst from the reaction mixture.