Synthesis of unsymmetrically substituted bipyridines by palladium catalyzed direct C H arylation of pyridine N oxides.
Substituted bipyridines were efficiently prepared by direct coupling between pyridine N oxides and halopyridines using a palladium catalyst. Pyridine N oxides with electron withdrawing substituents 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 architectures.
Organic letters