Flavanoid epoxides—XIII : Acid and base catalysed reactions of 2′-tosyloxychalcone epoxides. Mechanism of the algar-flynn-oyamada reaction

doi:10.1016/S0040-4020(01)93304-6

Tetrahedron

Volume 29, Issue 2, 1973, Pages 369-373

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Abstract

2′-Tosyloxychalcone epoxide (6a) on reaction with alkali gave flavonol (4a) while similar treatment of 6′-methoxy-2′-tosyloxychalcone epoxide (6b), both at room temperature and at the boiling point of the reaction medium, afforded 5-methoxyaurone (5b). The latter result indicates that an epoxide is not an intermediate in the production of flavanols from 2′-hydroxy-6′-methoxychalcone epoxides on treatment with alkaline hydrogen peroxide (AFO Reaction) at the higher temperature. Epoxide 6a on treatment with boron trifluoride etherate gave a mixture of flavanonol and flavonol while epoxide 6b gave formyldesoxybenzoin (9) under similar conditions.

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Flavanoid epoxides—XIII : Acid and base catalysed reactions of 2′-tosyloxychalcone epoxides. Mechanism of the algar-flynn-oyamada reaction

Abstract

J. Chem. Soc.

Org. Mass Spectrom.

Proc. Roy. Irish Acad.

J. Chem. Soc. Japan

Proc. Imp. Acad. Tokyo

J. Am. Chem. Soc.

Proc. Indian Acad. Sci.

J. Chem. Soc.