Significant Lability of Guaiacylglycerol β-Phenacyl Ether under Alkaline Conditions
作者:Aiko Imai、Tomoya Yokoyama、Yuji Matsumoto、Gyosuke Meshitsuka
DOI:10.1021/jf071147d
日期:2007.10.1
is the migration of the B-ring from the beta- to the alpha-position following the SNAr mechanism. Because this migration affords the alkaline labile phenolic alpha-O-4-type compound (XI), the formation of the quinone methide as well as the cleavage of the originally alkaline very stable alkyl-aryl ether bond is promoted. This promotion of the quinone methide formation explains why a relatively large
观察到二聚酚醛木质素模型化合物在B环上具有α-羰基的2-(2-乙氧基-4-甲酰基苯氧基)-1-(4-羟基-)的β-O-4键裂解3-甲氧基苯基)丙烷-1,3-二醇(I)在温和的厌氧碱性处理(0.45 mol / L NaOH,95摄氏度,0.8 MPa的N2)中非常快。这种现象与不带任何特定官能团的普通二聚酚醛木质素模型化合物的情况形成了鲜明的对比,1-(4-羟基-3-甲氧基苯基)-2-(2-甲氧基苯氧基)丙烷-1,3-二醇(II) 。最合理的机制是遵循SNAr机制的B环从β位置迁移到α位置。由于这种迁移会产生碱性不稳定的酚类α-O-4-型化合物(XI),促进了醌甲基化物的形成以及最初碱性非常稳定的烷基-芳基醚键的裂解。醌甲基化物形成的这种促进解释了为什么在氧-碱处理中由I产生相对大量的4-羟基-3-甲氧基苯甲醛(IV)。