Modifiable Sulfur Tethers as Directing Groups for Aromatic CH Acetoxylation Reactions
作者:Heinrich Richter、Stephan Beckendorf、Olga García Mancheño
DOI:10.1002/adsc.201000941
日期:2011.2.11
A designed new class of modifiable sulfur tethers for aromatic CH bond functionalizations is presented. As a model, the palladium-catalyzed directed acetoxylation reaction was studied. The more challenging sulfoxide tethers were the most effective in this transformation, showing a broad functionality tolerance, high S oxido-redox stability and no catalyst poisoning. Preliminary mechanistic studies
Palladium-Catalyzed Coupling of Arene C–H Bonds with Methyl- and Arylboron Reagents Assisted by the Removable 2-Pyridylsulfinyl Group
作者:José A. Romero-Revilla、Alfonso Garcı́a-Rubia、Ramón Goméz Arrayás、M. Ángeles Fernández-Ibáñez、Juan C. Carretero
DOI:10.1021/jo2018137
日期:2011.11.18
The Pd-II-catalyzed direct coupling of arene C-H bonds with organoboron reagents assisted by the 2-pyridylsulfinyl group is reported. Methylboronic acid and arylboronic acid neopentyl esters proved to be efficient coupling partners, furnishing methylated arenes and biaryl products in moderate to good yields. The 2-pyridylsulfinyl group can be easily removed to provide the free biaryls. The essential role of the 2-pyridyl unit in stabilizing the cyclopalladation complex was demonstrated by X-ray diffraction analysis of the palladacycle intermediate.