The Reaction of 3-Hydroxyflavones with Metal Salts

The reaction of 3-hydroxyflavones (1a–d) with lead(IV) acetate gave 1,2-diphenylethanediones (2a–d), 1,2-diphenyl-2-hydroxyethanones, 2-hydroxybenzoic acids (7 and 9), and benzoic acids (8 and 10), and the reaction with manganese(III) acetate yielded 2, 7, 8, 9, and 10. In addition to 2, 7, and 10, 6-methoxy-2-(4-methoxybenzoyloxy)-3(2H)-benzofuranone and 2-hydroxy-4-methoxybenzaldehyde were obtained in the reaction of 1c with manganese(III) acetate. It has been established by the studies of 14C-labelled compounds that the C(3) in the 3-hydroxyflavone was lost during the reaction.