Ethyl chloroformate → 6-bromo-5-methyl-3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione

Participants

Reaction Conditions

Reaction Steps

Step 1 A solution of 3-bromo-6-hydroxy-2-methyl-N-phenylbenzamide (Intermediate 16-1, 40 mg, 0.131 mmol) in pyridine (1 mL) was treated with ethyl chloroformate (0.015 mL, 0.157 mmol) at rt and the mixture was heated to 100° C. for 2 h. Additional ethyl chloroformate (0.015 mL, 0.157 mmol) was added and the mixture was stirred at 100° C. for 15 h. The mixture was cooled and diluted with EtOAc (80 mL), and the solution was washed with NaHCO3 (aq) (10 mL), water (2×10 mL) and brine (10 mL), and dried and concentrated. The residue was purified by column chromatography (eluting with a gradient from 95:5 to 70:30 hexane-EtOAc) to give 6-bromo-5-methyl-3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione (19 mg, 44%). 1H NMR (400 MHz, chloroform-d) δ 7.90 (1H, d, J=9.02 Hz), 7.43-7.68 (3H, m), 7.27-7.40 (2H, m), 7.12 (1H, d, J=8.80 Hz), 2.90 (3H, s). Mass spectrum m/z 332, 334 (M+H)+.

Provenance & Evidence