Lewis Acid Trapping of an Elusive Copper鈥揟osylnitrene Intermediate Using Scandium Triflate

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• 作者：Subrata Kundu ; Enrico Miceli ; Erik Farquhar ; Florian Felix Pfaff ; Uwe Kuhlmann ; Peter Hildebrandt ; Beatrice Braun ; Claudio Greco ; Kallol Ray
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：September 12, 2012
• 年：2012
• 卷：134
• 期：36
• 页码：14710-14713
• 全文大小：265K
• 年卷期：v.134,no.36(September 12, 2012)
• ISSN：1520-5126

文摘

High-valent copper鈥搉itrene intermediates have long been proposed to play a role in copper-catalyzed aziridination and amination reactions. However, such intermediates have eluded detection for decades, preventing the unambiguous assignments of mechanisms. Moreover, the electronic structure of the proposed copper鈥搉itrene intermediates has also been controversially discussed in the literature. These mechanistic questions and controversy have provided tremendous motivation to probe the accessibility and reactivity of Cu^III鈥揘R/Cu^IIN^{鈥?/sup>R species. In this paper, we report a breakthrough in this field that was achieved by trapping a transient copper鈥搕osylnitrene species, 3-Sc, in the presence of scandium triflate. The sufficient stability of 3-Sc at 鈭?0 掳C enabled its characterization with optical, resonance Raman, NMR, and X-ray absorption near-edge spectroscopies, which helped to establish its electronic structure as CuIIN鈥?/sup>Ts (Ts = tosyl group) and not CuIIINTs. 3-Sc can initiate tosylamination of cyclohexane, thereby suggesting CuIIN鈥?/sup>Ts cores as viable reactants in oxidation catalysis.}