Four-Electron Oxidation of Phenols to p-Benzoquinone Imines by a (Salen)ruthenium(VI) Nitrido Complex

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• 作者：Jianhui Xie ; Wai-Lun Man ; Chun-Yuen Wong ; Xiaoyong Chang ; Chi-Ming Che ; Tai-Chu Lau
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：May 11, 2016
• 年：2016
• 卷：138
• 期：18
• 页码：5817-5820
• 全文大小：371K
• 年卷期：0
• ISSN：1520-5126

文摘

Proton-coupled electron-transfer reactions of phenols have received considerable attention because of their fundamental interest and their relevance to many biological processes. Here we describe a remarkable four-electron oxidation of phenols by a (salen)ruthenium(VI) complex in the presence of pyridine in CH₃OH to afford (salen)ruthenium(II) p-benzoquinone imine complexes. Mechanistic studies indicate that this reaction occurs in two phases. The first phase is proposed to be a two-electron transfer process that involves electrophilic attack by Ru≡N at the phenol aromatic ring, followed by proton shift to generate a Ru(IV) p-hydroxyanilido intermediate. In the second phase the intermediate undergoes intramolecular two-electron transfer, followed by rapid deprotonation to give the Ru(II) p-benzoquinone imine product.