化物N-氧化物与化物基质对Rh (III) 催化氧化C-H键的功能化
Sharon R Neufeldt1, Gonzalo Jiménez-Osés1, John R Huckins2
1†Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
Journal of the American Chemical Society
|July 22, 2015
概括
由于较强的Rh相互作用,皮里丁N-氧化物基质在Rh-催化无效反应中表现出增强的反应性和C(2) 位点选择性. 计算研究揭示了不同的速度限制步骤和影响选择性的关键相互作用.
科学领域:
- 有机化学 有机化学
- 有机金属化学 有机金属化学
- 计算化学的计算化学
背景情况:
- 氨酸衍生物经历了与基因的Rh (III) 催化取消反应.
- 与N-氧化物相比,皮里丁基质表现出较慢的反应速率和较差的位点选择性 (C(2) -H与C(4) -H).
- 了解基质的反应性和选择性对于合成应用至关重要.
研究的目的:
- 以计算方式调查里丁N-氧化物基质中高反应性和位点选择性的起源.
- 为了比较Pyridine N-氧化物和Pyridine衍生物在Rh(III) 催化无效化中的反应机制.
- 阐明控制CH激活和基因插入步骤的因素.
主要方法:
- 使用密度函数理论 (DFT) 的计算.
- 分析了反应路径,过渡状态和能量障碍.
- 动态同位素效应研究和H/D交换实验提供了实验验证.
主要成果:
- 由于更强的指导组-Rh相互作用,皮里丁N-氧化物更具反应性.
- 阿尔基因插入是限制速度和选择性决定与dialkyl alkynes的N-氧化物.
- -H激活是限制皮里丁的2-功能化的速度,而基因插入则限制了4-功能化.
- 氧化的高C2选择性来自于合作的电子和硬质效应.
- 皮里丁基板对C(2) 和C(4) 功能化具有几乎相同的能量障碍,导致选择性差.
结论:
- 皮里丁N-氧化物增强的反应性和C(2) -选择性归因于与Rh催化剂的良好相互作用.
- C-H激活和基因插入步骤之间的相互作用决定了整体反应性和选择性.
- 计算发现得到实验证据的支持,提供了对反应机制的全面理解.
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