Controlling Site Selectivity in Pd-Catalyzed Oxidative Cross-Coupling Reactions
摘要:
This paper presents a detailed investigation of the factors controlling site selectivity in the Pd-mediated oxidative coupling of 1,3-disubstituted and 1,2,3-trisubstituted arenes (aryl -H) with cyclometalating substrates (L similar to C-H). The influence of both the concentration and the steric/electronic properties of the quinone promoter are studied in detail. In addition, the effect of steric/electronic modulation of the carboxylate ligand is discussed. Finally, we demonstrate that substitution of the carboxylate for a carbonate X-type ligand leads to a complete reversal in site selectivity for many arene substrates. The origins of these trends in site selectivity are discussed in the context of the mechanism of Pd-catalyzed oxidative cross-coupling.
Palladium-Catalyzed Direct CH Functionalization of Benzoquinone
作者:Sarah E. Walker、James A. Jordan-Hore、David G. Johnson、Stuart A. Macgregor、Ai-Lan Lee
DOI:10.1002/anie.201408054
日期:2014.12.8
A direct Pd‐catalyzed CHfunctionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents.
可以控制直接 Pd 催化的苯醌 (BQ) 的C H 官能化以得到单取代或双取代的 BQ,包括在一锅法中安装两个不同的基团。BQ 现在可以直接用芳基、杂芳基、环烷基和环烯基官能化,而且,反应在环境友好的水或丙酮作为溶剂中进行。