Copper‐Catalyzed Direct Cross‐Coupling of Compounds Containing Activated C–H/Heteroatom–H Bonds with <i>N</i>‐Tosylhydrazones

Abstract

Abstract Direct coupling between N ‐tosylhydrazones and various coupling partners such as 1,3‐azoles, alkynes, and heteroatoms in the presence of Cu catalysts has turned out to be an extremely attractive route for carbon–carbon and carbon–heteroatom bond formation. Recently, both intra‐ and intermolecular versions, along with cascade reactions involving sequential inter‐ and intramolecular coupling, have made a significant impact in synthetic chemistry. Emphasis has been placed on copper as catalyst to highlight the advantages of these methods over those involving several other late‐transition‐metal catalysts. The limited advancements to date leave ample opportunity for further investigation in this area, which still has a long way to go in the near future. The key intermediates in these reactions arise from a carbene migratory insertion process that can be terminated in numerous ways, resulting in the formation of a diverse range of pharmaceutically important scaffolds.