Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
J Org Chem. 2011 Sep 16;76(18):7301-15. doi: 10.1021/jo201179p. Epub 2011 Aug 2.
With the aim to find an efficient synthetic procedure for the construction of 2,3-diamino-2,3-dideoxy-β-D-mannuronic acids, we evaluated three mannosyl donors: (S)-phenyl 4,6-di-O-acetyl-2,3-diazido mannopyranoside, (S)-phenyl 2,3-diazido-4,6-O-benzylidene mannopyranoside, and (S)-phenyl 2,3-diazido mannopyranosyl methyl uronate. The first two mannosylating agents are rather unselective or slightly α-selective in their condensation with three different acceptors. The mannuronic acid donor on the other hand reliably provides the desired β-mannosidic linkage. A mechanistic rationale is put forward to account for the different behavior of the three donor types. Suitably protected 2,3-diazido mannuronic acids were employed to construct the all-cis-linked tetrasaccharide repeating unit of the capsular polysaccharide of Bacillus stearothermophilus , featuring two 2,3-diacetamido-2,3-dideoxy-β-D-mannuronic acids.
为了找到一种有效的 2,3-二氨基-2,3-二脱氧-β-D-甘露糖酸的合成方法，我们评估了三种甘露糖供体：（S）-苯基 4,6-二-O-乙酰基-2,3-二叠氮基甘露吡喃糖苷、（S）-苯基 2,3-二叠氮基-4,6-O-亚苄基甘露吡喃糖苷和（S）-苯基 2,3-二叠氮基甘露吡喃糖基甲基尿苷酸。前两种甘露糖基化试剂在与三种不同的受体缩合时，选择性不强或稍有α选择性。另一方面，甘露糖酸供体可靠地提供所需的β-甘露糖苷键。提出了一种机制上的基本原理来解释三种供体类型的不同行为。适当保护的 2,3-二叠氮基甘露糖酸被用于构建芽孢杆菌的荚膜多糖的全顺式连接四糖重复单元，其特征在于含有两个 2,3-二乙酰氨基-2,3-二脱氧-β-D-甘露糖酸。
