Copper-Catalyzed Radical C–C Bond Cleavage and [4+1] Annulation Cascade of Cycloketone Oxime Esters with Enaminothiones
作者:Yuan He、Jiang Lou、Kaikai Wu、Hongmei Wang、Zhengkun Yu
DOI:10.1021/acs.joc.8b03175
日期:2019.2.15
Carbon–carbon bond formation is among the most important reactions in organic synthesis. Reconstruction of a carbon–carbon bond through ring-opening C–C bond cleavage of a strained carbocycle usually occurs via a thermodynamically preferable pathway. However, carbon–carbon bond formation through thermodynamically less favorable C–C bond cleavage has seldom been documented. Herein, we disclose an unusual
碳-碳键的形成是有机合成中最重要的反应之一。通过张开的碳环的开环CC键裂解来重建碳-碳键通常是通过热力学上优选的途径进行的。但是,很少有文献报道通过热力学上不利的C-C键断裂形成碳-碳键。在本文中,我们公开了环酮肟酯在[4 + 1]环化反应中不寻常的C–C键裂解。在厌氧铜(I)催化下,对环酮肟酯进行区域选择性,热力学上较不利的自由基C-C键裂解,然后用烯胺硫酮进行环化;即α-硫代氧乙烯酮N,S-缩醛有效地提供了2-氰基烷基-氨基噻吩衍生物。环丁酮,-戊酮,-己酮和-庚酮肟酯可以作为环化反应中有效的C1结构单元。提出了亚氨基自由基机理,用于罕见的C–C键裂解/ [4 + 1]环合级联反应。