在有机化学中的血性联体:对离子化的替代效应
Antonio Ramírez1, Emil Lobkovsky, David B Collum
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA.
Journal of the American Chemical Society
|December 11, 2003
概括
研究人员探索了聚乙烯和氨基乙烯如何影响二醇胺介导的消除反应. 令人惊的是,联体结构并没有加速反应,一些替代剂甚至减缓了反应.
科学领域:
- 有机化学 有机化学
- 反应机制 反应机制
- 有机金属化学 有机金属化学
背景情况:
- 1,2-消除反应是有机合成的基础.
- 对各种应用来说,循环氨酸的合成至关重要.
- 二胺 (LDA) 是一种强大的非核基,通常用于消除.
研究的目的:
- 为了研究潜在的半性聚乙烯和氨基乙烯对LDA介导的1,2-消除1 - 环氧素到环氧素的影响.
- 阐明连接体结构和化在调节反应速率和途径中的作用.
主要方法:
- 使用大约50种不同的配体对1,2-消除反应进行实验研究.
- 动力学研究以确定速率规律和对联结体结构的依赖性.
- 计算研究包括半经验和DFT方法来分析化效应.
主要成果:
- 速率规律表明,对于选定的配体,基化单体基途径是可选的.
- 与预期相反,gem-dimethyl效应并没有加速反应;替代剂通常会减缓反应.
- 计算研究表明,与非化形式相比,替代联体的酸盐中的固体阻碍 (缩) 阻止了稳定.
- 一个特定的配体,MeOCH(2)CH(2)NMe(2),通过更高协调的单体路径独特促进了消除.
结论:
- 干结构在LDA介导的淘汰中起着复杂的作用,硬质因素往往主导电子效应.
- 化并不总是导致由于硬体约束而导致速率加速.
- 特定的连接体设计,如MeOCH(2) CH(2) NMe(2),可以为循环氨酸合成提供独特的反应途径.
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