Abstract
NbCl5 is found to be an efficient catalyst for the Pechmann condensation reaction of phenols and β-keto ester leading to the formation of coumarin derivatives in excellent yields under solvent-free conditions. The reaction protocol is simple and environmentally friendly.
ACKNOWLEDGMENTS
This work was financially supported by the Natural Science Foundation of Hebei (B2011204051), the Scientific Research Foundation of Education Department of Hebei Province (2010137), and the Natural Science Foundation of the Agricultural University of Hebei (2009-001).