Brønsted acidic ionic liquid as the efficient and reusable catalyst for synthesis of coumarins via Pechmann condensation under solvent-free conditions
- Pharmaceutical Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156, Islamic Republic of Iran
- Department of Chemistry, Faculty of Sciences, Najafabad Branch, Islamic Azad University, Najafabad, Esfahan, P.O. Box 517, Iran.
- Department of Science, Fasa Branch, Islamic Azad University, PO Box No. 364, Fasa 7461713591, Fars, Iran.
Abstract
A mild and efficient method has been developed for the preparation of substituted coumarins from reaction of various phenols with different β-ketoesters via Pechmann condensation in the presence of Brønsted acidic ionic liquid (N-(4-sulfonic acid) butyl triethylammonium hydrogen sulfate) as an effective catalyst under solvent-free conditions. Different phenols reacted with ethyl acetoacetate to produce the corresponding substituted coumarins in high to excellent yields and short reaction times. Moreover, [TEBSA][HSO4] has been used as an effective green catalyst for the synthesis of coumarin derivatives under solvent-free conditions. Using the relatively non-toxic (halogen-free) and reusable Brønsted acidic ionic liquid, high catalytic efficiency, high yields, short reaction times and straightforward work-up are advantages of this protocol.