[NH2:1][C:2]1[C:13]([Br:14])=[CH:12][C:5]2[C:6]([C:9](O)=[O:10])=[CH:7][O:8][C:4]=2[CH:3]=1.C[CH2:16][N:17]=C=NCCCN(C)C.C1C=CC2N(O)N=NC=2C=1.CCN(CC)CC.CN.Cl>CN(C=O)C>[NH2:1][C:2]1[C:13]([Br:14])=[CH:12][C:5]2[C:6]([C:9]([NH:17][CH3:16])=[O:10])=[CH:7][O:8][C:4]=2[CH:3]=1To a solution of 6-amino-5-bromobenzofuran-3-carboxylic acid (51 g, 199 mmol) in dry DMF (500 mL) were add EDCI (53.1 g, 298.77 mmol) and HOBT (40.4 g, 299 mmol). The reaction mixture was stirred at room temperature for 2 h, and then Et3N (60.5 g, 598 mmol) and MeNH2.HCl (40.3 g, 598 mmol) were added to the reaction mixture. After stirring for another 2 hours, the reaction mixture was concentrated in vacuum and 300 mL Na2CO3 (a.q.) was added to the mixture. The resulting solid was filtered to give the crude product, which was purified by column chromatography (DCM:MeOH=30:1) to give 6-amino-5-bromo-N-methylbenzofuran-3-carboxamide (38 g, yield: 71%). 1H-NMR (400 MHz, DMSO-d6) δ 8.19˜8.21 (m, 2H), 7.98 (s, 1H), 6.97 (s, 1H), 5.46 (br s, 2H), 2.75 (d, J=4.4 Hz, 3H).
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