Synthesis and reactions of 1-aryl-3-formyl-4,6-dinitro-1H-indazoles

The title compounds were prepared by the reactions of picrylacetaldehyde with aryldiazonium salts followed by the intramolecular cyclization of the resulting picrylglyoxal monoarylhydrazones, and the regiospecific substitution for the nitro group at the 4-position under the action of anionic N-, O- and S-nucleophiles was found.