Synfacts 2011(9): 0948-0948  
DOI: 10.1055/s-0030-1260995
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Copper-Catalyzed Three-Component Synthesis of 2H-Indazoles

Contributor(s): Victor Snieckus, Emilie David
M. R. Kumar, A. Park, N. Park, S. Lee*
Chonnam National University, Gwangju, Republic of Korea
Further Information

Publication History

Publication Date:
19 August 2011 (online)


The synthesis of 2H-indazoles is ­reported using a copper-catalyzed three-component reaction of 2-bromobenzaldehydes, primary amines, and sodium azide. CuI as catalyst and TMEDA as ligand were found to be the best combination to afford products in moderate to good yields. Aliphatic and (hetero)aromatic amines were tolerated, although sterically hindered and EWG aromatics gave lower yields. Control experiments were carried out to investigate the effect of copper catalyst. On the basis of these studies, the authors suggested that the reaction occurs first through A, which then undergoes a substitution by the azide in the presence of copper to get B. Activation of the terminal nitrogen of the azide by copper would then allow the attack of the benzylideneaniline nitrogen to form the N-N bond (C).