[Br:1][C:2]1[C:3]([N:19]([CH3:24])[S:20]([CH3:23])(=[O:22])=[O:21])=[CH:4][C:5]2[O:9][C:8]([C:10](OC)=[O:11])=[C:7]([C:14](=[O:17])[NH:15][CH3:16])[C:6]=2[CH:18]=1.O.[NH2:26][NH2:27]>CCO>[Br:1][C:2]1[C:3]([N:19]([CH3:24])[S:20]([CH3:23])(=[O:22])=[O:21])=[CH:4][C:5]2[O:9][C:8]([C:10]([NH:26][NH2:27])=[O:11])=[C:7]([C:14]([NH:15][CH3:16])=[O:17])[C:6]=2[CH:18]=1To a suspension of compound methyl 5-bromo-3-(methylcarbamoyl)-6-(N-methylmethylsulfonamido)benzofuran-2-carboxylate in EtOH was added hydrazine hydrate (421 mg, 7.16 mmol). The mixture was refluxed overnight. Then it was concentrated in vacuo and the resulting solid was washed with MeCN to give the compound 5-bromo-2-(hydrazinecarbonyl)-N-methyl-6-(N-methylmethylsulfonamido)benzofuran-3-carboxamide (600 mg, yield: 100%). It was used for the next step without further purification. 1H-NMR (DMSO-d6, 400 MHz) δ 10.33 (br s, 1H), 8.60 (s, 1H), 7.96 (s, 1H), 5.03 (br s, 3H), 3.22 (s, 3H), 3.20 (s, 3H), 2.87 (d, J=4.8 Hz, 3H). MS (M+H)+: 419/421.
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