Synthesis and conformational analysis of 6-C-methyl-substituted 2-acetamido-2-deoxy-beta-D-glucopyranosyl mono- and disaccharides.
Synthesis and conformational analysis of 6-C-methyl-substituted 2-acetamido-2-deoxy-beta-D-glucopyranosyl mono- and disaccharides.
复制标题
6-C-甲基取代的 2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖基单糖和二糖的合成和构象分析。
DOI：
10.1021/jo0485841
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Wei,Alexander
中科院分区：
文献类型：
--
作者：
Achkar,Jihane;Sanchez-Larraza,Isabel;Johnson,CarolA;Wei,Alexander
通过溶液NMR光谱研究了几种6-C-取代的2-乙酰氨基-2-脱氧-β-d-吡喃葡萄糖苷（β-d-GlcNAc单糖1a − 3a和1，4-连接的双糖苷1b −3b）。对（6S）-和（6 R）-C-甲基取代的β-d-GlcNAc单糖的构象分析表明，立体定向的甲基对环外C-5−C-6键施加了可预测的构象偏差，这由1H −1H和13 C −1H偶合常数确定。在甲醇-d4中进行变温NMR实验以确定来自两个最低能量构象的Δ Δ和Δ Δ S值。这些结果表明，虽然6-C-甲基取代对构象焓的影响与空间相互作用的经典原理雅阁，但溶液中的构象偏好也受到其他因素的强烈影响，如溶剂-溶质相互作用和溶剂重组。
Several 6-C-substituted 2-acetamido-2-deoxy-β-d-glucopyranosides (β-d-GlcNAc monosaccharides1a−3aand 1,4-linked disaccharides1b−3b) were studied by solution NMR spectroscopy. Conformational analysis of the (6S)- and (6R)-C-methyl-substituted β-d-GlcNAc monosaccharides indicates that the stereodefined methyl groups impose predictable conformational biases on the exocyclic C-5−C-6 bond, as determined by1H−1H and13C−1H coupling constants. Variable-temperature NMR experiments in methanol-d4were performed to determine ΔΔHand ΔΔSvalues derived from the two lowest energy conformers. These indicate that while the influence of 6-C-methyl substitution on conformational enthalpy is in accord with the classic principles of steric interactions, conformational preference in solution can also be strongly affected by other factors such as solvent−solute interactions and solvent reorganization.