Zhang Jing, Han Fu-She
CAS Key Lab of High-Performance Synthetic Rubber and Its Composite Materials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, China; The University of Chinese Academy of Sciences, Beijing 100864, China.
CAS Key Lab of High-Performance Synthetic Rubber and Its Composite Materials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, China.
iScience. 2019 Jul 26;17:256-266. doi: 10.1016/j.isci.2019.06.037. Epub 2019 Jul 4.
The [6.5.6]-tricyclic indole δ-lactam represents a common key intermediate for the synthesis of a broad variety of structurally intriguing indole alkaloids. The development of a method for the versatile and straightforward construction of such structural motif is of great importance for potential synthetic applications. Herein, we present a co-ligand-prompted Pd-catalyzed 6-exo-trig intramolecular cyclization of indolyl amides via the aerobic oxidative Heck cross-coupling. The method provided a general and efficient way for the construction of [6.5.6]-tricyclic indole δ-lactams. A mechanistic study suggests that a Pd/Pd catalytic cycle should be responsible for effective coupling, which represents a mechanistically alternative pathway when compared with the Pd/Pd cycle proposed for other related coupling reactions.
[6.5.6]-三环吲哚δ-内酰胺是合成多种结构引人入胜的吲哚生物碱的常见关键中间体。开发一种通用且直接构建此类结构基序的方法对于潜在的合成应用具有重要意义。在此，我们报道了一种共配体促进的钯催化吲哚酰胺的6-外环化分子内环化反应，该反应通过需氧氧化Heck交叉偶联实现。该方法为构建[6.5.6]-三环吲哚δ-内酰胺提供了一种通用且高效的途径。机理研究表明，Pd/Pd催化循环应负责有效偶联，与其他相关偶联反应提出的Pd/Pd循环相比，这代表了一种机理上的替代途径。
