Reactions of Imines, Nitriles, and Isocyanides with Pentaphenylborole: Coordination, Ring Expansion, C鈥揌 Bond Activation, and Hydrogen Migration Reactions

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• 作者：Kexuan Huang ; Shannon A. Couchman ; David J. D. Wilson ; Jason L. Dutton ; Caleb D. Martin
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：September 21, 2015
• 年：2015
• 卷：54
• 期：18
• 页码：8957-8968
• 全文大小：693K
• ISSN：1520-510X

文摘

The reactions of pentaphenylborole with imines, isocyanides, and acetonitrile were investigated experimentally and theoretically. On the basis of literature precedent, we envisioned that the dipolar substrates would undergo facile ring expansion reactions to yield new BNC₅ heterocycles. For acetonitrile and one particular imine, this ring expansion process was observed. However, in many cases, unexpected reactivity occurred. This included hydride migration of an imine ring expanded product and the ortho C鈥揌 bond activation of an aryl group of an imine if two phenyl groups were present on the 伪-carbon. A bulky group on the nitrogen atom of an imine prevented coordination to the boron center, and no reaction was observed, indicating that coordination to the borole is a critical step for any type of reaction to occur. Isocyanides made coordination complexes, but heating to induce further reactivity resulted in mixtures. The mechanisms were elucidated via DFT calculations, which complement the experimental findings.