反应详情

A mixture of crude ethyl 5-bromo-6-nitrobenzofuran-3-carboxylate (95 g, 302 mmol), iron filings (50.67 g, 907 mmol) and NH4Cl (97 g, 1.82 mol) in MeOH-THF—H2O (2:2:1, 1000 mL) were stirred at refluxing for 3 hours. After filtered and concentrated in vacuum, the residue was purified by column chromatography (eluted with PE:EA from 20:1 to 10:1) to furnish the pure product of ethyl 6-amino-5-bromobenzofuran-3-carboxylate (58.0 g, yield: 68%). 1H-NMR (DMSO-d6, 400 MHz) δ 8.46 (s, 1H), 7.85 (s, 1H), 7.03 (s, 1H), 5.55 (br s, 2H), 4.31 (q, J=7.2 Hz, 2H), 1.32 (t, J=7.2 Hz, 3H). MS (M+H)+: 284/286.

1. temperatureat refluxing for 3 hours
2. filtrationAfter filtered
3. concentrationconcentrated in vacuum
4. customthe residue was purified by column chromatography (eluted with PE:EA from 20:1 to 10:1)