ネジキの成分研究 (第3報)

Lyonisideの構造 その1

抄録

Methylation followed by hydrolysis of lyoniside (I) affords xylose and lyoniresinol dimethyl ether (II), C₂₄H₃₂O₈. Oxidation of (II) with chromium trioxide in glacial acetic acid gave 2, 6-dimethoxy-p-benzoquinone while the same oxidation in pyridine gave two kinds of γ-lactone with the same molecular composition. The latter lactones indicated the presence of asymmetrically substituted 1, 4-butylene glycol. Oxidation of (II) with potassium permanganate in pyridine and decarboxylation of the acid (V), m. p. 187°, C₂₀H₂₂O₉, so obtained gave 2, 3, 3′, 4′, 5′-hexamethoxybenzophenone (VI), which was identified by admixture with the compound prepared by a different route. Treatment of (I) with p-nitrobenzenediazonium chloride and methylation of the dye so obtained gave 3, 4, 5-trimethoxy-4′-nitroazobenzene (VII), which was identified with the compound obtained by the same treatment of syringic acid. These results indicate that (I) is a 5-substituted pyrogallol 1, 3-dimethyl ether. (II) possesses two alcoholic hydroxyls but no phenolic hydroxyl, and xylose must have been attached to one of them. Formula (I) is therefore proposed for lyoniside from the foregoing chemical evidences and from biosynthetic consideration.