AuBr
<sub>3</sub>
‐Catalyzed Chemoselective Annulation of Isocyanates with 2
<i>H</i>
‐Azirine
作者:Yufeng Wu、Bing Tian、Sina Witzel、Hongming Jin、Xianhai Tian、Matthias Rudolph、Frank Rominger、A. Stephen K. Hashmi
DOI:10.1002/chem.201804765
日期:2019.3.15
cyclization of isocyanates with 2H‐azirine was achieved with AuBr3 as catalyst. This transfer sets the stage for the synthesis of aromatic oxazole‐ureas in a tandem process. The addition of a catalytic amount of phosphite enhances the process enormously. The reaction can also be performed in a one‐pot process using benzoyl azide instead of isocyanate under the same conditions. A detailed study on the role of
以AuBr 3为催化剂,实现了2 H-叠氮基对异氰酸酯的化学选择性环化。这种转移为串联过程中芳族恶唑脲的合成奠定了基础。加入催化量的亚磷酸酯极大地改善了该过程。该反应也可以在相同条件下使用叠氮化苯甲酰代替异氰酸酯在单锅法中进行。对作为添加剂使用的亚磷酸酯的作用的详细研究表明,只有非配位的亚磷酸酯才能还原金(III),而金(I)配位的亚磷酸酯不会被氧化。伴随着金的还原,原位生成了HBr,事实证明它是与剩余的AuBr 3结合的实际促进剂。。酸的积极作用可以通过强的N–Au配位来解释,当溶液中存在少量质子酸时,它往往更容易断裂。