Water-mediated phosphorylative cyclodehydrogenation: An efficient preparation of flavones and flavanones

Abstract

A new synthetic strategy utilizing POCl₃-water for the conversion of 2′-hydroxychalcones to flavanones and flavones has been developed. The reagent efficiently promoted one-pot conversion of 2′-hydroxychalcones to flavones through flavanones involving cyclization and oxidative dehydrogenation. By changing the stoichiometery of the reagents, the reaction can be tuned to generate either flavanone or flavone. The developed protocol was found to be applicable for a variety of 2′-hydroxychalcones.

GRAPHICAL ABSTRACT

Keywords:

• Flavanones
• flavones
• 2′-hydroxychalcones
• oxidative cyclodehydrogenation
• POCl₃
• single-reagent-driven reactions
• water-mediated synthesis

Acknowledgments

The authors thank Dr. D. K. Dubey, Director, DRDE for his keen interest and encouragement. The authors also thank Dr. Avik Mazumdar and Mr. Ajeet Kumar for NMR support, Mrs. Tara Yadav for Elemental Analysis DRDE internal review committee for valuable inputs (DRDE/SC/013/2018).

Disclosure statement

We state that none of the authors have any conflict of interest in the context of this communication.