用含有亚的模板激活催化元选择性C-H键:对选择性的机制和起源进行计算研究

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Yun-Fang Yang¹, Gui-Juan Cheng, Peng Liu

¹Laboratory of Computational Chemistry and Drug Design and Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School , Shenzhen 518055, China.

Journal of the American Chemical Society

|December 10, 2013

概括

密度函数理论揭示了Pd-Ag异构体是使用化模板进行元选择性C-H化的关键. 这将帕拉引导到元位置,控制反应结果.

科学领域:

有机金属化学有机金属化学
催化剂是一种催化剂.
计算化学计算化学

背景情况:

催化C-H功能化对于有机合成至关重要.
在这些反应中实现区域选择性,特别是元选择性,仍然是一个挑战.
含酸盐的模板提供了指导CH激活的策略.

研究的目的:

阐明Pd(II) 催化C-H化中的元区域选择性的机制和起源.
调查不同催化物种在反应中的作用.
了解酸盐模板如何影响区域选择性.

主要方法:

使用密度函数理论 (DFT) 调查.
分析了四个关键步骤:C-H激活,基插入,β-化物消除和还原性消除.
对各种催化物种的评估:单体Pd(II),二体Pd2 ((OAc) 4),异体PdAg ((OAc) 3和三体Pd3 ((OAc) 6.

主要成果:

通过协同化-脱化 (CMD) 途径进行的C-H激活步骤决定了速率和区域选择性.
鉴定出Pd-Ag异构体过渡状态是超C-H激活最有利的途径.
亚基组与Ag协调,将Pd定位为元选择性C-H激活,超过二维Pd2的能量优势 (OAc) 4.

结论:

这种Pd-Ag异构体机制解释了在这些反应中观察到的高元选择性.
单质和三质Pd物种更喜欢 орто产品,需要更高的激活能量.
模板结构和扭曲能量显著影响反应机制和区域选择性,为新的催化剂设计提供了途径.

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