Reductive Couplings of 2-Halopyridines without External Ligand: Phosphine-Free Nickel-Catalyzed Synthesis of Symmetrical and Unsymmetrical 2,2′-Bipyridines
摘要:
An unexpectedly facile synthetic approach for symmetrical and unsymmetrical 2,2'-bipyridines through the Ni-catalyzed reductive couplings of 2-halopyridines was developed. The couplings were efficiently catalyzed by 5 mol % of NiCl2 center dot 6H(2)O without the use of external ligands. A variety of 2,2'-bipyridines including caerulomycin F have been efficiently synthesized.
Synthesis of 2,2′-Bipyridines via Suzuki-Miyaura Cross-Coupling
作者:Arne Lützen、Christoph Gütz
DOI:10.1055/s-0029-1217082
日期:2010.1
For a long time, the Suzuki-Miyauracross-couplingreaction could not be used for the synthesis of 2,2′-bipyridines due to the lack of sufficiently stable 2-pyridylboron compounds. Stabilized 2-pyridylboronic acid esters recently developed by Hodgson, however, were found to be ideally suited for this purpose. Two general protocols could be developed and demonstrated to be valuable alternatives, which