反应详情

A mixture of crude compound ethyl 5-bromo-2-cyclopropyl-6-nitrobenzofuran-3-carboxylate (8.5 g, 25 mmol), iron filings (4.1 g, 75 mmol) and NH4Cl (8 g, 150 mmol) in MeOH-THF—H2O (2:2:1, 100 mL) were stirred at reflux for 3 hours. After being 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-bromo-2-cyclopropylbenzofuran-3-carboxylate (7.00 g, yield: 91%). 1H-NMR (400 MHz, CDCl3) δ 7.93 (s, 1H), 6.75 (s, 1H), 4.40 (q, J=7.2 Hz, 2H), 4.11 (s, 2H), 2.94˜2.99 (m, 1H), 1.43 (t, J=7.2 Hz, 3H), 1.19˜1.21 (m, 2H), 1.12˜1.15 (m, 2H). MS (M+H)+: 324/326.

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