阐明C-4基对银酸捐赠体的立体指导作用
Floor Ter Braak1, Frank F J de Kleijne1, Teun van Wieringen1,2
1Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands.
Angewandte Chemie (International ed. in English)
|February 23, 2026
概括
合成1,2-cis甘氨基酸键是非常具有挑战性的. 研究人员发现,C-4乙基不通过二氧化离子直接进行银河化,而是通过屏蔽供体,从而使选择性α-银河化物形成.
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
- 立体选择性反应
背景情况:
- 1,2-cis甘氨酸结合物的立体选择性合成,特别是银河酸,是一个重大挑战.
- 众所周知,C-4乙烯基保护组在银河系化中会影响立体选择性,但机制尚不清楚.
研究的目的:
- 为了阐明C-4基在银河化中的立体导向效应背后的机制.
- 研究邻近群体参与与固体障碍在控制立体化学结果中的作用.
主要方法:
- 使用各种带有C-4乙烯保护的银河系酶捐赠体进行了糖化反应.
- 交换NMR光谱法用于检测短暂的中间体.
- 密度函数理论 (DFT) 的计算被用来建模过渡状态和反应途径.
主要成果:
- 没有发现C-4二氧化离子形成的实验证据,反驳了邻近群体的参与.
- 交换NMR检测到β-glycosyl三酸盐,这可以通过SN2-like位移导致α-galactosides.
- DFT的计算表明,C-4酸基团在固体上阻碍了银河系基素捐赠者的β面,有利于α产品的形成.
结论:
- 在银河化过程中,C-4基的立体导向作用主要是由于硬质阻碍,而不是邻近组的参与.
- 了解这种机制为开发改进的立体选择性糖化方法提供了基本的见解.
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