A Cu-Catalyzed C-N Bond Coupling Route to Substituted Indazoles

Significance

A general methodology for the synthesis of indazoles based on a traditional Ullmann reaction is reported. Thus, copper-catalyzed C-N bond coupling of ortho-halo aromatic ketones and carboxylic acids with hydrazines leads to intermediates which undergo dehydration to indazoles in poor to very good yields depending on structural variation. The scope of the reaction was insufficiently investigated.