牛蒡子成分研究 (第6報)
Arctigenin及びIsoarctigeninの不斉炭素中心の配位について
1952 年 72 巻 3 号 p. 288-291
詳細
1952 年 72 巻 3 号 p. 288-291
l-α- (3-Methoxy-4-hydroxybenzyl) -β- (3′, 4′-dimethoxybenzyl) -succinic acid (XIV), m.p. 188°, [α]D-16.8°, undergoes transition by acetic anhydride to an oil of d-form (XIV′) that fails to give a strychnine salt, which seems to show that it is a diastereoisomer different from the d-type antipode of (XIV). Treatment of the ethyl ester of (XIV′) with sodium alcoxide results in its reversion to the crystals of (XIV). This has clearly shown that (XIV) is a trans-l-type compound that is formed by similar mechanism as the transition of cis-hexahydrophthalic acid to a trans-type and of cis-acid ester to trans-type reported by Hückel, and transition of trans-1, 2, 3, 4-tetrahydronaphthalene-2, 3-dicarboxylic acid to cis-anhydride and of cis-ester to trans-acid reported by Haworth. In the synthesis of arctigenin, it is assumed that the trans-l-type of (XIV) first forms cis-d-anhydride which is reduced by Al-amalgam to cis-d-butyrolactone which undergoes another transition to a trans-l-type by the action of sodium alcoxide or alcoholic sodium hydroxide.
