Potassium tert-Butoxide Promoted Intramolecular Amination of 1-Aryl-2- (2-nitrobenzylidene)hydrazines: Efficient Synthesis of 1-Aryl-1H-indazoles

1-Aryl-2-(2-nitrobenzylidene)hydrazines readily undergo intramolecular amination to afford 1-aryl-1H-indazole derivatives. The reaction was conducted in the presence of potassium tert-butoxide in N,N-dimethylformamide (DMF) at 100 °C and all products were obtained in good yields. Displacement of the nitro group was achieved in the absence of significant electron-withdrawing substituents such as nitro, cyanide, diazo, or carbonyl groups.