Synthesis of Unsymmetrically Substituted Bipyridines by Palladium-Catalyzed Direct C−H Arylation of Pyridine <i>N</i>-Oxides
作者:Sasa Duric、C. Christoph Tzschucke
DOI:10.1021/ol200565u
日期:2011.5.6
Substituted bipyridines were efficiently prepared by direct coupling between pyridine N-oxides and halopyridines using a palladium catalyst. Pyridine N-oxides with electron-withdrawing substitutents gave the best yields. This method allows the convenient preparation of 2,2′-, 2,3′-, and 2,4′-bipyridines which are useful as functionalized ligands for metal complexes or as building blocks for supramolecular
Palladium-Catalyzed Directed Halogenation of Bipyridine <i>N</i>-Oxides
作者:Sina P. Zucker、Friedrich Wossidlo、Manuela Weber、Dieter Lentz、C. Christoph Tzschucke
DOI:10.1021/acs.joc.7b00444
日期:2017.6.2
The palladium-catalyzed directed C–H halogenation of bipyridine N-oxides was investigated. Using NCS or NBS (N-chloro- or N-bromosuccinimide) and 5 mol % Pd(OAc)2 in chlorobenzene (0.10 molar) at 110 °C, pyridine-directed functionalization took place and 3-chloro- or 3-bromobipyridine N-oxides were obtained in high yields. The reaction is sensitive to steric hindrance by 4- and 6′-substituents. Only