Z-Selective Ethenolysis with a Ruthenium Metathesis Catalyst: Experiment and Theory

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• 作者：Hiroshi Miyazaki ; Myles B. Herbert ; Peng Liu ; Xiaofei Dong ; Xiufang Xu ; Benjamin K. Keitz ; Thay Ung ; Garik Mkrtumyan ; K. N. Houk ; Robert H. Grubbs
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：April 17, 2013
• 年：2013
• 卷：135
• 期：15
• 页码：5848-5858
• 全文大小：674K
• 年卷期：v.135,no.15(April 17, 2013)
• ISSN：1520-5126

文摘

The Z-selective ethenolysis activity of chelated ruthenium metathesis catalysts was investigated with experiment and theory. A five-membered chelated catalyst that was successfully employed in Z-selective cross metathesis reactions has now been found to be highly active for Z-selective ethenolysis at low ethylene pressures, while tolerating a wide variety of functional groups. This phenomenon also affects its activity in cross metathesis reactions and prohibits crossover reactions of internal olefins via trisubstituted ruthenacyclobutane intermediates. In contrast, a related catalyst containing a six-membered chelated architecture is not active for ethenolysis and seems to react through different pathways more reminiscent of previous generations of ruthenium catalysts. Computational investigations of the effects of substitution on relevant transition states and ruthenacyclobutane intermediates revealed that the differences of activities are attributed to the steric repulsions of the anionic ligand with the chelating groups.