Departamento de Química Orgánica, Universidad de Valencia, Avda. Vicent Andrés Estellés s/n 46100-Burjassot, Valencia (Spain), Fax: (+34) 963544939.
Chemistry. 2014 Jan 13;20(3):683-8. doi: 10.1002/chem.201304087. Epub 2013 Dec 6.
The competition between π- and dual σ,π-gold-activation modes is revealed in the gold(I)-catalyzed heterocyclization of 1-(o-ethynylaryl)urea. A noticeable effect of various ligands in gold complexes on the choice of these activation modes is described. The cationic Au(IPr) (IPr=2,6-bis(diisopropylphenyl)imidazol-2-ylidene) complex cleanly promotes the π activation of terminal alkynes, whereas Au(PtBu3 ) favors intermediate σ,π species. In this experimental and mechanistic study, which includes kinetic and cross-over experiments, several σ-gold, σ,π-gold, and other gold polynuclear reaction intermediates have been isolated and identified by NMR spectroscopy, X-ray diffraction, or MALDI spectrometry. The ligand control in the simultaneous or alternative π- and σ,π-activation modes is also supported by deuterium-labeling experiments.
在金（I）催化的 1-（邻炔基芳基）脲杂环化反应中，揭示了π-和双σ,π-金活化模式之间的竞争。描述了金配合物中各种配体对这些活化模式选择的显著影响。阳离子[Au(IPr)]+（IPr=2,6-双（二异丙基苯基）咪唑-2-亚基）配合物可干净地促进末端炔烃的π活化，而[Au(PtBu3)]+有利于中间σ,π物种。在这项实验和机理研究中，包括动力学和交叉实验，通过 NMR 光谱、X 射线衍射或 MALDI 光谱学分离和鉴定了几个σ-金、σ,π-金和其他多核金反应中间体。氘标记实验也支持配体对同时或交替的π-和σ,π-活化模式的控制。
