在Rh (I) 催化 (5 + 2) 循环添加中区域选择性的电子和固体控制:实验和理论
Peng Liu1, Lauren E Sirois, Paul Ha-Yeon Cheong
1Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA.
Journal of the American Chemical Society
|July 1, 2010
概括
乙烯基cyclopropanes (VCPs) 和alkynes之间的Rh(I) 催化 (5 + 2) 循环添加显示出基于替代物位置的可预测的区域选择性. 过渡状态中的绝缘和电子效应决定了这些重要的有机反应的结果.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 反应机制的反应机制
背景情况:
- 乙烯基cyclopropanes (VCPs) 是有机合成的多功能构建块.
- ((I) 催化 (5 + 2) 循环添加为复杂的循环结构提供了强大的途径.
- 这些反应中的区域选择性,特别是与不对称的基因,仍然是一个需要详细研究的领域.
研究的目的:
- 调查Rh(I) 催化 (5 + 2) 循环添加在VCP和非对称基因之间的区域选择性.
- 建立一个用于控制区域化学结果的预测模型.
- 了解替代剂对反应选择性的影响.
主要方法:
- 涉及各种替代VCP和基的实验研究.
- 密度函数理论 (DFT) 计算用于机械分析.
- 对反应产物的分析以确定区域选择性比率.
主要成果:
- 对于具有终端基替代的VCP,观察到高区域选择性 (>20:1),与硬质模型一致.
- 对于具有内部基替代的VCPs,发现了可变的区域选择性 (范围从>20:1到1:2.3不等).
- 为了解释观察到的趋势,提出了一种结合基替代剂电子效应的精细模型.
结论:
- Rh (I) 催化 (5 + 2) 循环添加的区域选择性受到固体和电子因素的影响.
- 终端VCP替代导致可预测的区域选择性.
- 内部VCP替代和取电子的基基团可以通过过渡状态稳定改变选择性.
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