for the construction of n-membered (n>3) N-heterocycles, rely upon two chemical operations by involving sequential nucleophilic and electrophilic C-N bond formations. Here, we report a highly efficient cascade of alkyne insertion/C-H activation/amination for the rapid preparation of a myriad of tricyclic indoles, in a single-step transformation, by using bifunctional secondary hydroxylamines. Noteworthy
Selective C(sp
<sup>3</sup>
)−N Bond Cleavage of
<i>N</i>
,
<i>N</i>
‐Dialkyl Tertiary Amines with the Loss of a Large Alkyl Group via an S
<sub>N</sub>
1 Pathway
alkyne-tethered aryl iodides with tertiary hydroxylamines has been developed for the rapid assembly of 3,4-fused tricyclic indoles with a removable aliphatic N-substituent. This domino reaction was realized by alkyne-directed palladacycle formation, electrophilic amination with tertiary hydroxylamines and selective C(sp3)−N bond cleavage with the loss of the larger alkyl group via an SN1 path.
已经开发了一种新型 Pd 0催化的 [2+2+1] 炔烃连接芳基碘化物与叔羟胺的环化反应,用于快速组装具有可去除脂肪族N取代基的 3,4-稠合三环吲哚。这种多米诺骨牌反应是通过炔烃定向的钯环形成、叔羟胺的亲电胺化和选择性 C(sp 3 )-N 键断裂以及通过 S N 1 路径损失更大的烷基来实现的。
Fine-tuning hydroxylamines as single-nitrogen sources for Pd(0)-catalyzed diamination of o-bromo(or chloro)-biaryls
Transition metal-catalyzed diamination by hydroxylamines is a common approach for making three-membered aziridines, while its use for building the larger N-heterocycles is still underdeveloped. Herein, we report an efficient Pd(0)-catalyzed inter-molecular [4+1] annulation of o-bromo(or chloro)-biaryls with bifunctional secondary hydroxylamines for the one-step assembly of synthetically useful carbazoles
羟胺的过渡金属催化二化是制备三元氮丙啶的常用方法,而其用于构建较大的N-杂环的用途仍未开发。在此,我们报告了一种有效的 Pd(0) 催化的分子间 [4+1] 环化邻溴(或氯)-联芳基与双功能仲羟胺,用于一步组装合成有用的咔唑。值得注意的是,这种多米诺骨牌反应的关键是明智地选择氨基源和 Pd(0)-催化剂,以便在具有不稳定 NO 的羟胺存在下将芳基卤化物氧化加成到 Pd(0)-物种中。键。
Cobalt(II)-Catalyzed Activation of C(sp<sup>3</sup>)–H Bonds: Organic Oxidant Enabled Selective Functionalization
develop a new “cobalt(II)/organic oxidant” catalytic system for the selective activation of 1°, 2°, and 3° C(sp3)–H bonds to construct C–N and C–O bonds, respectively. The method highlights the use of an organic compound (TsNHOPiv or its analogues) as an emerging oxidant and thus provides a flexible strategy for the preparation of indoline and benzoxazine derivatives. Attractive advantages of this cobalt
Palladium(II)-Catalyzed [2+2+1] Annulation of Alkynes and Hydroxylamines: A Rodox-Neutral Approach to Fully Substituted Pyrroles
作者:Jiaxing Bai、Nengni Xu、Hui Wang、Xinjun Luan
DOI:10.1021/acs.orglett.2c01925
日期:2022.7.22
A palladium-catalyzed [2+2+1] annulation of alkynes and hydroxylamines has been developed for the rapid construction of fully substituted pyrroles. This transformation involves sequential nucleophilic-addition of hydroxylamine to alkyne, alkyne migratory insertion, and synergistic demetallization cyclization, which provides a redox-neutral annulationapproach to pyrrole derivatives. Moreover, the strategy