Algar-Flynn-Oyamada反応の改変

概要

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Several attempts were made to extend the Algar-Flynn-Oyamada synthesis of flavonols (3-hydroxyflavones) to the synthesis of dihydroflavonols (3-hydroxyflavanones).　1. The alkaline hydrogen peroxide oxidation of 2'-hydroxychalcones (the socalled Algar-Flynn-Oyamada reaction) has been found to yield dihydroflavonols besides flavonols in the presence of a minium quantity of alkali. In this paper, the proper pH (10.5) to form the former as the major product in this reaction was determined.　2. In view of the known tendency of dihydroflavonols to undergo further oxidation under alkaline conditions, the acidic oxidation of 2'-hydroxychalcones with peracetic acid or pertungstic acid was carried out to prevent the forming dihydroflavonol from being further oxidized. Actually, no satisfactory result was obtained in either case.　3. Finally, it was found that polyhydroxychalcones bearing hydroxyl groups in 2' and other positions gave the corresponding epoxides by protecting all the hydroxyl groups by methoxymethylation during the course of the alkaline per-oxide oxidation, and that the resulting poly (methoxymethoxy) chalcone oxides, when warmed with acid, readily cyclized to polyhydroxydihydroflavonols, with the simultaneous splitting of all the O-methoxymethyl groups.
山形大学の論文
1967-01-20