立体电子控制在添加核素对胺离子的核素中
1Department of Chemistry, University of California-San Diego, La Jolla, California 92093-0358, USA.
Journal of the American Chemical Society
|July 18, 2001
概括
核友添加中的立体电子控制用四胺离子量化. 偏好轴向攻击,但反应产生 cis/trans 立体异构体,显示出对反应性的弱立体电子效应.
科学领域:
- 有机化学 有机化学
- 立体化学是一种立体化学.
- 反应机制 反应机制
背景情况:
- 核性添加反应是有机合成的基础.
- 立体电子效应显著影响反应通路和产品分布.
- 氨基离子为研究反应控制提供了独特的结构特征.
研究的目的:
- 量化测量核友添加反应中的立体电子控制.
- 研究立体电子和立体因素对反应结果的影响.
- 为了确定动力学和热力学控制在离子反应中的相对贡献.
主要方法:
- 1,3-二甲基-5--1,4,5,6-四胺离子的合成和反应.
- 核性添加与各种各样的卡巴尼和化物.
- 使用质子核磁共振 (1H NMR) 分析动力和热力学产品分布.
- 酸催化均衡以确定热力学产物比率.
主要成果:
- 对胺离子的核性添加通过两个不同的途径发生,其中偏好了轴性攻击.
- 与各种核友的反应产生了 cis 和 trans 立体同位素的混合物.
- 发现立体电子效应很弱,对反应性贡献大约1kcal/mol.
结论:
- 立体电子效应在这个四胺系统的反应性中起到很小的作用.
- 固态和立体电子因素都有助于观察到的立体化学结果.
- 这项研究提供了对控制核友添加反应的力量平衡的定量见解.
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