在甲基化物中对基基的迁移:配置和构造决定了动力学
Leon M Friedrich1, Clemens Lütjohann1, Bernd Hartke2
1Otto Diels Institute of Organic Chemistry, Christiana Albertina University of Kiel, Otto-Hahn-Platz 3-4, 24118, Kiel, Germany.
在帕拉尼特罗 (PNP) 甘酸乙烯中,亚利尔迁移在 cis 导向的基基团之间更快. 这项研究揭示了迁移率与糖形态能量障碍相关,影响碳水化合物合成.
科学领域:
- 碳水化合物化学 碳水化合物化学
- 有机化学 有机化学
- 物理有机化学 有机化学
背景情况:
- 帕-尼特罗 (PNP) 糖化乙是合成功能性碳水化合物的关键中间体.
- 这些化合物在中性条件下稳定,但在基本条件下容易发生基迁移,这使得像Zemplén脱基化这样的反应复杂化.
研究的目的:
- 调查O-PNP替代甲基糖化物中基迁移的动力学和机制.
- 确定基导向和糖类立体化学对迁移速率的影响.
- 阐明反应中间体和离子协调在迁移过程中的作用.
主要方法:
- 利用核磁共振 (NMR) 谱学来监测甲醇/甲氧化物中各种甲基糖化物 (曼诺,银,葡萄糖,其他系列) 中的迁移动力学.
- 运用密度函数理论 (DFT) 计算来确定迁移过程的能量概况,识别关键中间体和过渡状态.
主要成果:
- 在 cis 导向的基基团之间,与 trans 导向的基团相比,阿里尔迁移率显著更快.
- 观察到的迁移速率常数按照以下顺序进行:Alt > Man > Gal > Glc.
- 计算表明,迈森海默复合体是对尼托基迁移的中间体,而离子协调在调节能量配置中起着至关重要的作用.
结论:
- 基基团的立体化学方向和糖椅反转的结构能量障碍是PNP糖化物中基迁移率的关键因素.
- 了解这些迁移途径对于优化涉及糖化物的合成策略和防止碳水化合物功能化过程中的不良副作用至关重要.
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