[N+:1]([C:4]1[CH:12]=[CH:11][CH:10]=[C:9]2[C:5]=1[CH:6]=[N:7][NH:8]2)([O-:3])=[O:2].[OH-].[K+].[I:15]I.S(=O)(O)[O-].[Na+]>CN(C)C=O>[I:15][C:6]1[C:5]2[C:9](=[CH:10][CH:11]=[CH:12][C:4]=2[N+:1]([O-:3])=[O:2])[NH:8][N:7]=1A solution of 4-nitro-1H-indazole (50.0 g; 306 mmol) in N,N-dimethylformamide (600 mL) was cooled to 5° C. under a nitrogen atmosphere with stirring. Powdered potassium hydroxide (68.8 g; 1226 mmol) was added. A solution of iodine (156 g; 613 mmol) in DMF (200 mL) was added slowly to the reaction mixture over 2 hours maintaining the temperature between 5 and 10° C. The mixture was stirred at 25° C. for 24 hours. Additional iodine (39.0 g; 153.2 mmol) and potassium hydroxide (17.2 g; 306.5 mmol) was added. The mixture was stirred at 25° C. for a further 12 hours. The reaction mixture was added to an aqueous solution of sodium bisulfite (10% solution; 3300 mL) with stirring. The resulting precipitate was collected by filtration and washed with water. The material was dried in a vacuum oven at 40° C. The material was dissolved in methylene chloride/methanol (10:1; 1.5 L) and filtered through Celite® to remove inorganic impurities. Concentration of the solution under vacuum gave 3-iodo-4-nitro-1H-indazole as a yellow solid (75 g).
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