Synthesis of 2,2’-Bipyridines by Transition Metal-Catalyzed Alkyne/Nitrile [2 + 2 + 2] Cycloaddition Reactions

2,2'-Bipyridines are of great importance in the fields of catalysis, coordination chemistry, supramolecular chemistry, macromolecular chemistry and photochemistry.Recently, the metal-catalyzed [2 + 2 + 2]-type cycloaddition reaction of alkynes and nitriles has attracted considerable interest as a straightforward, atom-economical route to substituted pyridines and methods have been extensively applied to bipyridine synthesis.Developments in the field of 2,2'-bipyridine synthesis through alkyne/nitrile [2 + 2 + 2] cycloaddition reactions catalyzed by transition metals are reviewed in this article involving two types of fully intramolecular reaction, five types of partially intramolecular reaction and fully intermolecular reactions.CONTENTS 1. Introduction 2.