反应详情

温度

70 °C

A solution of 3-amino-4-hydroxy-benzoic acid methyl ester (4.2 g, 25.4 mmol) in dimethylformamide (85 mL) was treated with K2CO3 (14.2 g, 102.9 mmol, 4 equiv.) and 1,2-dibromoethane (19.3 g, 102.9 mmol, 4 equiv.). The mixture was stirred at 70° C. overnight, then filtered to remove the solids. The filtrate was removed under vacuo, and the residue was purified by flash chromatography (heptane/ethyl acetate gradient) to yield 3,4-dihydro-2H-benzo[1,4]oxazine-6-carboxylic acid methyl ester, 3.65 g (73%) as a light yellow solid, MS (ISP): m/e=235.1 (M+CH3CN+.); δH (300 MHz; CDCl3) 7.36 (1H, dd, J=8.5, 2.0), 7.30 (1H, d, J=2.0), 6.78 (1H, d, J=8.5), 4.30 (2H, m); 3.85 (3H, s), 3.43 (2H, m).

1. filtrationfiltered
2. customto remove the solids
3. customThe filtrate was removed under vacuo
4. customthe residue was purified by flash chromatography (heptane/ethyl acetate gradient)