Potassium Carbonate → 2-(6-Bromo-3-oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-propionic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a suspension of 6-bromo-4H-benzo[1,4]oxazin-3-one (27 g, 118.4 mmol) and K2CO3 (49.1 g, 355.2 mmol) in acetone (200 mL) was added 2-bromo-propionic acid ethyl ester (32.1 g, 177.6 mmol) and the reaction mixture was heated at 70° C. for 5 h. The reaction mixture was cooled to ambient temperature and the solvent was removed in vacuo and the residue was dissolved in DCM (50 mL). The organic phase was washed with water (3×20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was evaporated to dryness and the residue was purified by chromatography on silica gel (eluting with 5% EtOAc in petroleum ether) to give 2-(6-bromo-3-oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-propionic acid ethyl ester as a colorless liquid (32.5 g, 100 mmol, 84%). 1H NMR (CDCl3, 400 MHz): δ 7.09 (dd, J=8 Hz, J=2 Hz, 1H), 6.94 (d, J=2.0 Hz, 1H), 6.90 (d, J=8.4 Hz, 1H), 5.28 (q, J=14.8 Hz, 1H), 5.21 (q, J=5.4 Hz, 1H), 4.55 (d, J=15.2 Hz, 2H), 4.17 (m, 1H), 1.63 (d, J=1.2 Hz, 3H), 1.22 (t, J=1.2 Hz, 3H).

Provenance & Evidence