Model studies on the analysis of pyruvic acid acetal-containing polysaccharides by the reductive-cleavage method
作者:Samuel G. Zeller、Gary R. Gray
DOI:10.1016/0008-6215(90)84299-a
日期:1990.5
6-(1-methoxycarbonylethylidene) acetal was quite stable to reductive-cleavage conditions but isomerization of the initial R,S mixture of diastereomers to the more-stable S diastereoisomer was noted. In addition, a slow, regiospecific, reductive ring-opening of the acetal was observed to give 6-O-[1-(methoxycarbonyl)ethyl] derivatives. The 4,6-(hydroxyisopropylidene) acetal was very unstable under reductive-cleavage
使2,3-二-O-甲基-α-D-吡喃葡萄糖苷的甲基的4,6-O-(1-甲氧基羰基亚乙基),-(羟基异亚丙基)和-(甲氧基异亚丙基)缩醛在存在下进行还原裂解。三乙基硅烷和三甲基甲硅烷基甲磺酸硼三氟硼醚醚(Me3SiOMs-BF3.Et2O),BF3.Et2O或三甲基甲硅烷基三氟甲磺酸硼酸酯(Me3SiOSO2CF3)和产物的摩尔分数是反应时间的函数。4,6-(1-甲氧基羰基亚乙基)乙缩醛在还原裂解条件下相当稳定,但是注意到将非对映异构体的初始R,S混合物异构化为更稳定的S非对映异构体。另外,观察到乙缩醛的缓慢的区域特异性的还原性开环,得到6-O- [1-(甲氧基羰基)乙基]衍生物。4,在还原裂解条件下6-(羟基异亚丙基)乙缩醛非常不稳定。Me3SiOMs-BF3.Et2O和Me3SiOSO2CF3都通过中间体6- [1-(羟甲基)乙基]醚催化完全除去了该基团,但BF3.Et2O得到了产物混合