Synthesis of Substituted 2,2'-Bipyridines by Cobalt-Catalyzed Cycloaddition Reactions of Nitriles and 1,6-Diynes with Exclusive Regioselectivity

摘要

2,2'-bipyridines are of great importance as the substructure of biologically active compounds and particularly as a ligand capable of attaching to various metal atoms and,therefore,development of their synthesis is desired.We have recently developed a facile formation of substituted pyridines by [2 + 2 + 2] cycloaddition reaction of alpha,omega-diynes and nitriles by using a 1,2-bis(diphenylphosphino)ethane (dppe)/CoCl,-6H2O/Zn catalyst,where unactivated nitiles such as acetonitrile and benzonitrile reacted smoothly under mild reaction conditions.