ZrOCl2•8H2O/SiO2: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Silica gel supported zirconyl chloride octahydrate was found to be an efficient and recyclable catalyst for the synthesis of a series of biologically important molecules in high turnover numbers and rates. Several substituted coumarins can be prepared in high yield and purity by direct reaction of beta-keto esters and phenol derivatives in the presence of a catalytic amount of ZrOCl(2 center dot)8H(2)O/SiO2 as Lewis acid and at ambient temperature under solvent-free conditions. This method which is called Pechmann condensation is a very easy and a rapid reaction for the synthesis of coumarin derivatives. (C) 2011 Elsevier B.V. All rights reserved.