An unambiguous and practical synthesis of Oroxylin A: a commonly misidentified flavone.

Hosahalli P Hemantha, Rajendran Ramanujam, Muhammed Majeed, Kalyanam Nagabhushanam

Natural product research 2021 May

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Oroxylin A, a major flavonoid in the extracts of Oroxylum indicum as well as Scutellaria baicalensis possesses useful medicinal properties. Many of the published routes claiming the synthesis of Oroxylin A (1) have in fact led to a regioisomer Negletein that was misinterpreted as Oroxylin A. In the present work, we describe a novel, straight-forward and scalable semi-synthetic approach for rapid access to the title compound, the structure of which is unambiguously secured by NMR and X-ray crystallographic analysis of a derivative. This work also encompasses the synthesis of a glycosylated derivative of Oroxylin A viz OAGME (2), which has marked pharmacological importance.

Citation

Hosahalli P Hemantha, Rajendran Ramanujam, Muhammed Majeed, Kalyanam Nagabhushanam. An unambiguous and practical synthesis of Oroxylin A: a commonly misidentified flavone. Natural product research. 2021 May;35(9):1413-1420