Copper-Catalyzed Direct Cross-Coupling of Compounds Containing Activated C-H/Heteroatom-H Bonds with N-Tosylhydrazones.

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. [ABSTRACT FROM AUTHOR]