我们展示了一类新的超交联聚合物(HCP)平台锚定的单点异质化 Pd-NHC 催化剂,用于多用途 C-H 功能化反应。这一新类别由一组三种催化剂代表,即HCP-B- Me NHC-Pd、HCP-B- Bn NHC-Pd和HCP-TPM- Me NHC-Pd,在结构特征上有变化锚定聚合物平台。所有三种催化剂都通过各种固态表征和分析技术(如 X 射线光电子能谱、13C 交叉极化魔角自旋核磁共振、场发射扫描电子显微镜、能量色散 X 射线分析、热重分析和电感耦合等离子体-光发射光谱法。三种经常使用且非常有用的 C-H 官能化反应,即 C-H 卤化、乙酰氧基化和芳基化,用新催化剂进行了测试,发现它们具有高度的相容性和成功性。使用HCP-TPM- Me NHC-Pd在催化剂的作用下,卤化、乙酰氧基化和芳基化反应的官能化产物的产率分别高达 85%、75% 和 70%。这种新系统提供了诸如增强的活性、异质性和可回收性等苛刻的特性,使其成为非均相
Hydrogen peroxide based oxidation of hydrazines using HBr catalyst
作者:Jian Wang、Zichao Ma、Wanting Du、Liming Shao
DOI:10.1016/j.tet.2021.132546
日期:2021.12
Azo compounds (RN = NR′) are an important class of organic molecules that find wide application in organic synthesis. Herein, we report an efficient, practical and metal-free oxidation of hydrazines (RNH-NHR’) to azo compounds using 5 mol% HBr and hydrogen peroxide as terminal oxidant. This new method has been demonstrated by 40 examples with excellent yields. In addition, we showcased two examples
Convenient Electrocatalytic Synthesis of Azobenzenes from Nitroaromatic Derivatives Using SmI<sub>2</sub>
作者:Yu-Feng Zhang、Mohamed Mellah
DOI:10.1021/acscatal.7b02940
日期:2017.12.1
The synthesis of azobenzenes has been a long-standing challenge. Their current preparation at a preparative or industrial scale requires stoichiometric amounts of environmentally unfriendly reactants. Herein, we demonstrate that the catalytic use of electrogenerated samarium diiodide (SmI2) could promote, in one-step synthesis, the reduction of nitrobenzenes into azobenzenes in high yields under mild
Gold-Catalyzed Direct Hydrogenative Coupling of Nitroarenes To Synthesize Aromatic Azo Compounds
作者:Xiang Liu、Hai-Qian Li、Sen Ye、Yong-Mei Liu、He-Yong He、Yong Cao
DOI:10.1002/anie.201404543
日期:2014.7.14
The azo linkage is a prominent chemical motif which has found numerous applications in materials science, pharmaceuticals, and agrochemicals. Described herein is a sustainable heterogeneous‐gold‐catalyzed synthesis of azo arenes. Available nitroarenes are deoxygenated and linked selectively by the formation of NN bonds using molecular H2 without any external additives. As a result of a unique and
A detailed mechanism study on the anion ligand promoted selective C–H bond fluorination is reported. The role of the anion ligand has been clarified by experimentalevidence and DFT calculations. Moreover, the nitrate promoted C–F bond reductive elimination enabled a selective C–H bond fluorination of various symmetric and asymmetric azobenzenes to access diverse o-fluoroanilines.