Montmorillonite-KSF mediated one step synthesis of pyranochromene derivatives

One-Pot Synthesis of 4H-Pyrano[3,2-c]coumarin Derivatives Catalyzed by Deep Eutectic Solvent

4H-Pyrano[3,2-c]coumarin derivatives are an important class of pharmaceutical compounds that are expensive to prepare by previously reported methods. An efficient and green method was developed to obtain these derivatives using the deep eutectic solvent (DES) zinc chloride/acetamide (n:n = 1:4), which acted as both the catalyst and the solvent for the reaction. An aromatic aldehyde, 4-hydroxycoumarin, and cyanoacetate were used as the substrates. The DES, substrate molar ratio, diluent type, temperature, and reaction time were optimized to obtain the 4H-pyrano[3,2-c]coumarin derivatives from a range of aromatic aldehydes in a single step in moderate to high yields and under mild reaction conditions.