Sodium Carbonate → 6-(3-Bromo-5-fluorophenyl)-4,4-dimethyl-1,4-dihydrobenzo[d][1,3]oxazin-2-one

Participants

Reaction Conditions

Reaction Steps

A mixture of (1,4-dihydro-4,4-dimethyl-2-oxo-2H-3,1-benzoxazin-6-yl)boronic acid (2.22 g, 10 mmol), 1,3-dibromo-5-fluorobenzene (3.05 g, 12 mmol), tetrakis(triphenylphosphine)palladium (0) (0.6 g, 0.52 mmol), and sodium carbonate (2.2 g, 21 mmol) in a mixture of DME and water (70 mL/15 mL) was degassed to remove the oxygen and then heated at 85° C. under a blanket of nitrogen for 3 hours. The reaction mixture was cooled to ambient temperature and quenched with a saturated aqueous ammonium chloride solution (20 mL). Ethyl acetate (100 mL) was added and organic layer was separated. The aqueous layer was extracted with ethyl acetate (3×30 mL). The combined organic layers were washed with brine and dried with MgSO4. The solvent was removed in vacuo and the residue was purified by a silica gel flash chromatography (hexane:ethyl acetate/1:1) to give 6-(3-bromo-5-fluorophenyl)-4,4-dimethyl-1,4-dihydrobenzo[d][1,3]oxazin-2-one as a white solid (1.4 g, 40%): mp 182–183° C.; 1H-NMR (DMSO-d6) δ 10.36 (s, 1H, D2O exchangeable), 7.78 (s, 1H), 7.58–7.65 (m, 3H), 7.49 (dd, 1H, J=8.3, 1.8 Hz), 6.96 (d, 1H, J=8.5 Hz), 1.69 (s, 6H); 19F-NMR (DMSO-d6) δ 112.46 (m, 1F); MS(CI) m/z 352([M+H]+, 78%), 350([M+H]+, 75%). Anal. Calc. For C16H13BrFNO2: C, 54.88, H, 3.74, N, 4.00. Found: C, 54.83, H, 3.82, N, 3.95.

Provenance & Evidence