对于立体选择性引入β-阿拉比诺化的实践方法
Xiangming Zhu1, Sameer Kawatkar, Yu Rao
1Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, USA.
Journal of the American Chemical Society
|September 7, 2006
概括
一种新的方法通过锁定一个关键的中间体,使得β-阿拉比诺化的立体选择性合成成为可能. 这种方法利用了一种新型的保护组,确保有效形成所需的β-糖酸化合物链接.
科学领域:
- 碳水化合物化学 碳水化合物化学
- 有机合成 有机合成
- 葡萄糖基酶化是指葡萄糖基酶化的过程.
背景情况:
- 对β-阿拉比诺化的立体选择性合成具有挑战性.
- 控制甘氨基基捐赠体的形状对于选择性至关重要.
研究的目的:
- 开发一种实用和立体选择的方法来引入β-阿拉比诺化.
- 设计一种新型的甘氨酸供体,有利于β-面核友性攻击.
主要方法:
- 对阿拉比诺富拉诺西尔氧碳离子的形态分析.
- 设计和合成一种具有3,5-O-di-tert-butylsilane保护组的新型甘地捐赠剂.
- 用各种受体进行糖基化反应.
主要成果:
- 这种新型的甘氨基基捐赠者被锁定在有利于贝塔面攻击的形状中.
- 在糖化反应中实现了出色的β选择性.
- 该方法通过合成阿拉比诺·加拉克坦的片段来验证该方法.
结论:
- 已经建立了用于立体选择性β-阿拉比诺酸合成的强大而有效的方法.
- 开发的葡萄糖糖捐赠和保护组策略为碳水化合物合成提供了强大的工具.
- 这种方法对复杂碳水化合物的合成有影响,比如阿拉伯.
相关概念视频
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A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
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If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
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