Studies on Benzochromones. VI. Syntheses and Ring Isomerization of 2-Methyl-5-methoxy-6, 7-benzochromone and 2-Methyl-5-methoxy-7, 8-benzochromone.

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2-Methyl-5-methoxy-6, 7-benzochromone (VIII), and 2-methyl-5-methoxy-7, 8-benzochromone (IV) were synthesized from 2-acetylnaphthalene-1, 3-diol (I), and it was found that VIII underwent irreversible ring isomerization to form 2-methyl-5-hydroxy-7, 8-benzochromone (III) during demethylation with hydriodic acid.