体加速的C-H激活反应:证据表明机制的切换
Keary M Engle1, Dong-Hui Wang, Jin-Quan Yu
1Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Journal of the American Chemical Society
|September 22, 2010
概括
单N受保护的氨基酸显著加快了酸的有氧化C-H化. 这种连接器调整通过将C-H裂变机制从电友拉转移到质子抽象来提高反应速率和基质范围.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 有机金属化学 有机金属化学
背景情况:
- ((II) 催化的C-H化反应对于合成复杂的有机分子至关重要.
- 干设计对于优化催化剂性能和反应结果至关重要.
- 乙酸是各种合成转化中的重要基质.
研究的目的:
- 研究单N受保护的氨基酸作为有氧Pd(II) 催化C-H烯酸酸的配体的作用.
- 系统调整连接物以提高反应效率,基质范围和催化剂周转率.
- 为了阐明负责观察到的速度加速的机械路径.
主要方法:
- 最初的速度研究以确定反应动力学.
- 使用各种单-N-受保护的氨基酸进行系统的连接器调整.
- 分子间竞争研究探讨速度决定的步骤.
- 动态同位素效应 (KIE) 实验用于研究C-H键裂解机制.
主要成果:
- 观察到与mono-N受保护的氨基酸联体反应速率的显著加速.
- 通过配体优化实现了基质范围,反应速率和催化剂周转率的显著改进.
- 证据表明,C-H裂变步骤的加速是速度增加的主要原因.
- 动力学数据表明,从电友拉到C-H裂变的质子抽象发生了机械的转变.
结论:
- 单N受保护的氨基酸是酸的有氧Pd(II) 催化C-H烯化非常有效的配体.
- 连接体调整可以深刻地影响反应动力学和机制,从而提高催化性能.
- 观察到的速率提升归因于C-H裂变机制的开关,有利于对电友拉的质子抽象.
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