Algar-Flynn-Oyamada reaction

The Algar–Flynn–Oyamada reaction is a chemical reaction whereby a chalcone undergoes an oxidative cyclization to form a flavonol.

There are several possible mechanisms to explain this reaction, however, these reaction mechanisms have not been elucidated. What is known is that a two-stage mechanism exists. First, dihydroflavonol is formed, which then subsequently oxidized to form a flavonol.

One point should be noticed is that those mechanisms which have an epoxide to be an intermediate are excluded,which should be obtained by the oxidation of the double bond with hydrogen peroxide in Prileschajew reaction. Gormley et al. have shown that the reaction does not proceed through an epoxide.

The probable mechanisms are thus two possibilities:

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