Green One-Pot Pseudo-Four Component Synthesis of Substituted 5-Cyano-2-imino-4-aryl/ heteroaryl-6-(phenylthio)-2H-pyran-3-carboxylic Acid Catalyzed by Montmorillonite K-10 Clay

Abstract

A synthetic method of substituted 5-cyano-2-imino-4-aryl/heteroaryl-6-(phenylthio)-2H-pyran-3-carboxylic acid (4a-d) using Montmorillonite K-10 clay as catalyst was developed via one-pot pseudo-four-component reaction. Various aldehydes and thiophenols exhibit swift reactivity with cyanoacetic acid, resulting in satisfactory to exceptional yields (ranging from 70% to 90%) within an exceptionally short reaction duration of 0.75 to 1.5 h. The structural characterization of the synthesized compounds was conducted through IR, 1H, 13C NMR and elemental analysis. Safer technique, simple work-up as well as reusability of the catalyst for two runs are the characteristic features of this method. This multicomponent one-pot reaction approach demonstrates a straightforward synthetic strategy for the formation of two novel C-C bonds, one C-S bond, one C-O bond, and the formation of a new ring structure. Additionally, this reaction exhibits high efficiency as all the reactants are completely utilized.