NHC-Stabilized Gold(I) Complexes: Suitable Catalysts for 6-<i>exo</i>-dig Heterocyclization of 1-(<i>o</i>-Ethynylaryl)ureas
作者:Ana Gimeno、Mercedes Medio-Simón、Carmen Ramírez de Arellano、Gregorio Asensio、Ana B. Cuenca
DOI:10.1021/ol100595s
日期:2010.5.7
3-substituted 1-(o-ethynylaryl)ureas 1 selectively undergo either 6-exo-dig or 5-endo-dig cyclization (to give 4-methylene-3,4-quinazolin-2-ones 2 or indoles 3, respectively) depending on the choice of the metal, ligand, and reaction conditions. The best results (up to 96% yield) in the preparation of the hydroamination products 2 are achieved with the highly bulky NHC-stabilized cationic gold(I) complex
3-取代的1-(ø -ethynylaryl)脲1选择性地经历或者6-外型-Dig或5-内切-Dig环化(以得到4-亚甲基-3,4-喹唑啉-2-酮2或吲哚3分别)取决于金属,配体和反应条件的选择。用高度笨重的NHC稳定的阳离子金(I)络合物[Au(IPr)] +可达到制备加氢胺化产品2的最佳结果(最高96%的产率)。相反地,带有内部炔烃的脲导致5-内切-环化模式,而与所使用的金(I)配合物无关。而在N处取代基的性质-3对观察到的区域化学没有任何影响,但在某些情况下会影响这些转化的效率。