与硫酸盐脱离组能力相匹配的甘基捐赠反应允许SN2甘化
Ming-Hua Zhuo1, David J Wilbur1, Eugene E Kwan2
1Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , Massachusetts 02155 , United States.
Journal of the American Chemical Society
|September 26, 2019
概括
通过将硫化激活剂与糖供体相匹配,可以实现高度选择性的β-糖化反应. 这种方法依赖于类似SN2的机制,避免碳水化合物合成中的传统保护组.
科学领域:
- 碳水化合物化学
- 有机合成
- 立体选择反应
背景情况:
- 寡糖合成通常依赖于保护群体进行立体控制.
- 在糖化过程中实现高β选择性仍然是一个挑战.
- 现有的方法可能与敏感的功能组不兼容.
研究的目的:
- 开发一种高度选择性β糖化反应的新策略.
- 在不依赖酸或敏感的保护组的情况下实现立体控制.
- 阐明观察到的β选择性的机制.
主要方法:
- 酸硫激活剂和甘氨酸供体半乙烯的电子相匹配
- 使用类似于SN2的机制,涉及α-glycosyl arylsulfonate的立体反转.
- 使用核磁共振 (NMR) 光谱.
- 进行动态同位素效应 (KIE) 测量.
- 执行密度函数理论 (DFT) 的计算.
主要成果:
- 已证明具有高度选择性的β糖化反应.
- 与常见的酸敏感保护组显示兼容性.
- 确定了α-glycosyl arylsulfonate的立体反转为β-选择性的来源.
- 机理学研究支持SN2类途径.
结论:
- 已经建立了一种新的方法来实现糖化中的β选择性.
- 这一战略为传统的依赖集团的保护方法提供了替代方案.
- 这些发现提供了对立体选择性糖化更深入的机制理解.
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