反应详情

To a solution of ethyl 2-(6-acetoxy-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)propanoate (13 g, 40.0 mmol) in THF (100 mL) was added morpholine (10.4 mL, 120 mmol) and the reaction mixture was heated at reflux for 18 h. The reaction mixture was cooled to ambient temperature, filtered and the filtrate was concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 5% EtOAc in petroleum ether) to give ethyl 2-(7-fluoro-6-hydroxy-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)propanoate (11 g, 80%) as a white solid. 1H NMR (CDCl3, 400 MHz): δ 6.78 (d, J=10.4 Hz, 1H), 6.49 (d, J=8.4 Hz, 1H), 5.20 (m, 2H), 4.57 (q, J=14.8 Hz, 2H), 4.20 (m, 2H), 1.58 (d, J=7.2 Hz, 3H), 1.19 (t, 3H).

1. temperaturethe reaction mixture was heated
2. temperatureat reflux for 18 h
3. filtrationfiltered
4. concentrationthe filtrate was concentrated in vacuo
5. customThe residue was purified by column chromatography on silica gel (eluting with 5% EtOAc in petroleum ether)