Hydrogen Activation by an Aromatic Triphosphabenzene
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- 作者：Lauren E. Longobardi ; Christopher A. Russell ; Michael Green ; Nell S. Townsend ; Kun Wang ; Arthur J. Holmes ; Simon B. Duckett ; John E. McGrady ; Douglas W. Stephan
- 刊名：Journal of the American Chemical Society
- 出版年：2014
- 出版时间：September 24, 2014
- 年：2014
- 卷：136
- 期：38
- 页码：13453-13457
- 全文大小：335K
- ISSN：1520-5126
文摘
Aromatic hydrogenation is a challenging transformation typically requiring alkali or transition metal reagents and/or harsh conditions to facilitate the process. In sharp contrast, the aromatic heterocycle 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene is shown to be reduced under 4 atm of H2 to give [3.1.0]bicylo reduction products, with the structure of the major isomer being confirmed by X-ray crystallography. NMR studies show this reaction proceeds via a reversible 1,4-H2 addition to generate an intermediate species, which undergoes an irreversible suprafacial hydride shift concurrent with P鈥揚 bond formation to give the isolated products. Further, para-hydrogen experiments confirmed the addition of H2 to triphosphabenzene is a bimolecular process. Density functional theory (DFT) calculations show that facile distortion of the planar triphosphabenzene toward a boat-conformation provides a suprafacial combination of vacant acceptor and donor orbitals that permits this direct and uncatalyzed reduction of the aromatic molecule.