[CH3:1][O:2][C:3](=[O:13])[C:4]1[CH:9]=[C:8]([I:10])[C:7]([CH3:11])=[C:6]([NH2:12])[CH:5]=1.[N+:14]([O-])(OCCC(C)C)=O>C(O)(=O)C>[CH3:1][O:2][C:3]([C:4]1[CH:5]=[C:6]2[C:7]([CH:11]=[N:14][NH:12]2)=[C:8]([I:10])[CH:9]=1)=[O:13]To a solution of 3-amino-5-iodo-4-methyl-benzoic acid methyl ester (1.22 g, 4.21 mmol) in acetic acid (20 mL) was added isoamyl nitrate (0.675 mL, 4.63 mmol). The mixture was stirred at room temperature for 30 minutes and then concentrated under reduced pressure. The residue was partitioned between dichloromethane and saturated aqueous sodium bicarbonate. The organic layer was separated, dried over MgSO4, filtered and concentrated under reduced pressure. The residue was purified by column chromatography to give 1.15 g (91%) of 4-iodo-1H-indazole-6-carboxylic acid methyl ester, MS (M+H)=303.
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