Sodium Perborate Tetrahydrate–Mediated Transformations of 2′-Hydroxychalcones to Flavanones, Flavones, and 3′, 5′-Diiodoflavone Under Mild, Environmentally Friendly Conditions

Abstract

Sodium perborate tetrahydrate has been utilized as a nucleophilic catalyst for facile conversion of 2′-hydroxychalcones to flavanones in warm aqueous acetonitrile, and then these chalcones, upon oxidative cyclization in warm acetic acid with an excess of the same reagent, afforded flavones in acceptable yields. One-pot synthesis of 3′,5′-diiodoflavone has been accomplished by diacetoxyiodobenzene-catalyzed iodination of 2′-hydroxychalcone with tetra-n-butylammonium iodide in acetic acid in the presence of sodium perborate as a terminal oxidant.

GRAPHICAL ABSTRACT

Keywords:

• 3′,5′-Diiodoflavone
• flavanone
• flavone
• 2′-hydroxychalcone
• sodium perborate tetrahydrate

ACKNOWLEDGMENTS

S. C. thanks to the Council of Scientific and Industrial Research (SRF-NET), New Delhi, and S. K. B. thanks the University of Kalyani for financial assistance by way of a research fellowship. Facilities provided by a great from the Department of Science and Technology–Funing for Infrastructure in Science and Technology, government of India, are also acknowledged.

Notes

^a The reactions were carried out on a 1-mmol scale of 1a at 50–60 °C using 4 mL of solvent each case.

^b Isolated yield after chromatographic separation.

^a The known compounds exhibit spectral data (FT-IR, ¹H CNMR, ¹³CNMR, MS) and melting points in agreement with those reported in the literature.

^b Isolated yield after column chromatographic separation.