C(sp3)鈥揊 Bond Activation of CF3-Substituted Anilines with Catalytically Generated Silicon Cations: Spectroscopic Evidence for a Hydride-Bridged Ru鈥揝 Dimer in the Catalytic Cycle
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- 作者：Timo Stahl ; Hendrik F. T. Klare ; Martin Oestreich
- 刊名：The Journal of the American Chemical Society
- 出版年：2013
- 出版时间：January 30, 2013
- 年：2013
- 卷：135
- 期：4
- 页码：1248-1251
- 全文大小：328K
- 年卷期：v.135,no.4(January 30, 2013)
- ISSN：1520-5126
文摘
Heterolytic splitting of the Si鈥揌 bond mediated by a Ru鈥揝 bond forms a sulfur-stabilized silicon cation that is sufficiently electrophilic to abstract fluoride from CF3 groups attached to selected anilines. The ability of the Ru鈥揌 complex, generated in the cooperative activation step, to intramolecularly transfer its hydride to the intermediate carbenium ion (stabilized in the form of a cationic thioether complex) is markedly dependent on the electronic nature of its phosphine ligand. An electron-deficient phosphine thwarts the reduction step but, based on the Ru-S catalyst, half of an equivalent of an added alkoxide not only facilitates but also accelerates the catalysis. The intriguing effect is rationalized by the formation of a hydride-bridged Ru鈥揝 dimer that was detected by 1H NMR spectroscopy. A refined catalytic cycle is proposed.