Through-Space 1,4-Palladium Migration and 1,2-Aryl Shift: Direct Access to Dibenzo[<i>a</i>,<i>c</i>]carbazoles through a Triple CH Functionalization Cascade
作者:Samir Kumar Bhunia、Arghya Polley、Ramalingam Natarajan、Ranjan Jana
DOI:10.1002/chem.201503474
日期:2015.11.16
A palladium‐catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2‐arylindoles and diaryliodonium salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected “through‐space” 1,4‐palladium migration to the 2‐aryl moiety, by remote CH bond activation followed by CH arylation with diaryliodonium salt, and an unprecedented 1,2‐aryl shift
据报道,钯催化快速地从容易获得的2-芳基吲哚和二芳基碘鎓盐中合成了二苯并稠合的咔唑。有趣的是,在吲哚进行亲电性C3 palladation之后,通过远距离的CH键活化,随后的CH芳基与二芳基碘鎓盐的偶合,意外地“穿空” 1,4-钯迁移至2芳基部分发生1,2-芳基转移。最后,在C2位置的分子内交叉脱氢偶联(CDC)可高产率提供二苯并[ a,c ]咔唑。值得注意的是,目前的迁移环空是通过三个CH键激活而发生的,一个CC键断裂,并在一次操作中同时构建三个新的CC键。