Direct Chemical Synthesis of the β-Mannans: Linear and Block Syntheses of the Alternating β-(1→3)-β-(1→4)-Mannan Common to <i>Rhodotorula </i><i>glutinis</i>, <i>Rhodotorula </i><i>mucilaginosa</i>, and <i>Leptospira </i><i>biflexa</i>
作者:David Crich、Wenju Li、Hongmei Li
DOI:10.1021/ja0471931
日期:2004.11.1
Two stereocontrolled syntheses of a methyl glycoside of an alternating β-(1→4)-β-(1→3)-mannohexaose, representative of the mannan from Rhodotorula glutinis, Rhodotorula mucilaginosa, and Leptospira biflexa, are described. Both syntheses employ a combination of 4,6-O-benzylidene- and 4,6-O-p-methoxybenzylidene acetal-protected donors to achieve stereocontrolled formation of the β-mannoside linkage.
描述了交替 β-(1→4)-β-(1→3)-甘露六糖的甲基糖苷的两种立体控制合成,代表了来自粘红酵母、粘液红酵母和双弯曲钩端螺旋体的甘露聚糖。两种合成均采用 4,6-O-亚苄基和 4,6-Op-甲氧基亚苄基缩醛保护供体的组合,以实现 β-甘露糖苷键的立体控制形成。第一个合成是线性合成,并且始终进行高度立体控制,总产率为 1.9%。第二个合成,即嵌段合成,利用了两个三糖的偶联,得到了更短的序列和 4.4% 的总产率,尽管关键步骤的选择性很差。