Bifunctional Phosphine Ligand Enabled Gold‐Catalyzed Alkynamide Cycloisomerization: Access to Electron‐Rich 2‐Aminofurans and Their Diels–Alder Adducts
作者:Xingguang Li、Xu Ma、Zhixun Wang、Pei‐Nian Liu、Liming Zhang
DOI:10.1002/anie.201908598
日期:2019.11.25
By using biphenyl-2-ylphosphines functionalized with a remote tertiary amino group as a ligand, readily available acetylenic amides are directly converted into 2-aminofurans devoid of any electron-withdrawing and hence deactivating/stabilizing substituents. These highly electron-rich furans have rarely been prepared, let alone applied in synthesis, because of their high reactivities and low stabilities
通过使用被远端叔氨基官能化的联苯-2-基膦作为配体,容易获得的炔属酰胺被直接转化为2-氨基呋喃,而没有任何吸电子和失活/稳定的取代基。这些高电子富集的呋喃很少制备,更不用说用于合成了,因为它们具有与呋喃环的富电子性质相关的高反应性和低稳定性。在这项工作中,这些反应性呋喃可以顺利进行原位分子间Diels-Alder反应,以提供高度官能化/取代的苯胺产品,或通过分子内化合物以高收率或优异的收率提供咔唑-4-羧酸酯。