反应详情

To a mixture of NaHCO3 (5.38 g, 64.0 mmol) and urea hydrogen peroxide (6.02 g, 64.0 mmol) in DCM (60 mL) at 0° C. was added ethyl 2-(6-acetyl-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)propanoate (6.6 g, 21.34 mmol). The reaction mixture was stirred for 10 min then TFAA (5.94 mL, 42.7 mmol) was added dropwise. The reaction mixture was stirred at 0° C. for 1 h and then allowed to warm to ambient temperature and stirred for 3 days. The reaction mixture was diluted with DCM (30 mL) and washed with water (30 mL). The combined organic layers were dried over anhydrous MgSO4, filtered and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 15% EtOAc in petroleum ether) to give ethyl 2-(6-acetoxy-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)propanoate and starting material as a white solid (5.9 g, 85%). 1H NMR (CDCl3, 400 MHz): δ 6.85 (d, J=10 Hz, 1H), 6.59 (d, J=6.8 Hz, 1H), 5.23 (m, 1H), 4.57 (q, J1=15.2 Hz, J2=14.8 Hz, 2H), 4.17 (m, 2H), 2.29 (s, 3H), 1.58 (d, J=7.2 Hz, 3H), 1.17 (t, 3H).

1. stirringThe reaction mixture was stirred at 0° C. for 1 h
2. stirringstirred for 3 days
3. washwashed with water (30 mL)
4. dry with materialThe combined organic layers were dried over anhydrous MgSO4
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customThe residue was purified by column chromatography on silica gel (eluting with 15% EtOAc in petroleum ether)