Competitive cascade cyclization of 2′-tosyloxychalcones: An easy access to thioflavones and thioaurones

Abstract

A new and efficient approach for the synthesis of thioflavones and thioaurones by competitive cascade cyclization of 2′-tosyloxychalcones has been developed. 2′-Tosyloxychalcones were smoothly converted into thioflavones and thioaurones by incorporation of sulfur atom using elemental sulfur and triethylamine in DMSO with good yields. The advantages of the methodology are the formation of both thioflavones and thioaurones in a single step. Easily accessible substrates, mild reaction conditions and compatibility with a broad range of functional groups make this protocol clean and inexpensive.

Graphical Abstract

Keywords:

• Cyclization
• sulfur
• thioaurone
• thioflavone
• 2′-tosyloxychalcone

Acknowledgments

We sincerely thank Sri Gokaraju Ganga Raju, Chairman, and Mr. Gokaraju Rama Raju, Director, Laila Impex Research Center, for support and encouragement.