反应详情

8-Fluoro-1H-benzo[d][1,3]oxazine-2,4-dione (10.0 g, 55.2 mmol) was dissolved in tetrahydrofuran (200 mL, 2000 mmol) at 0° C. 2.0 M Ethylamine in tetrahydrofuran (41 mL) was added and the reaction was stirred for 2 hours. The reaction was concentrated under reduced pressure and azeotroped with toluene (50 mL). Ethyl ether (200 mL) was added and the precipitate (the acid byproduct formed by hydrolysis) was removed by filtration. The filtrate was concentrated under reduced pressure and the product was purified by silica gel chromatography using a gradient of 0-60% EtOAc/hex as the eluting solvent to obtain 2-amino-N-ethyl-3-fluoro-benzamide as a pale yellow solid (9.02 g, 90%). m.p.=60° C.; LCMS (m/e) 183 (M+H); 1H-NMR (CDCl3, 400 MHz) δ 7.11 (d, 1H, J=8.0 Hz), 7.09-7.02 (m, 1H), 6.62-6.54 (m, 1H), 6.05 (bs, 1H), 5.61 (bs, 2H), 3.52-3.43 (m, 2H), 1.26 (t, 3H, J=6.6 Hz).

1. concentrationThe reaction was concentrated under reduced pressure
2. customazeotroped with toluene (50 mL)
3. additionEthyl ether (200 mL) was added
4. customthe precipitate (the acid byproduct formed by hydrolysis)
5. customwas removed by filtration
6. concentrationThe filtrate was concentrated under reduced pressure
7. customthe product was purified by silica gel chromatography