Convenient Preparation of Pyrano Benzopyranes in Aqueous Media

Abstract

The three‐component reaction of aldehyde, malononitrile, and 4‐hydroxy coumarin has been efficiently performed in aqueous K₂CO₃ using a simple, clean, environmentally benign, novel procedure employing microwave irradiation. The observed yields and enhancement in reaction rates can be attributed to the uniform heating effect of microwave. The microwave‐accelerated reaction technique not only eliminates the use of external base and organic solvents but also requires only water in both the reaction step and workup, thus rendering the whole procedure into a truly ecofriendly protocol.

Keywords:

• Aqueous K₂CO₃
• environmentally benign
• microwave irradiation
• pyrano[3,2‐c]benzopyran

Acknowledgments

M. Kidwai and S. Saxena are thankful to University Grants Commission, New Delhi, for the financial assistance.