Cl.[Br:2][C:3]1[C:12]2[O:11][C:10]([CH3:14])([CH3:13])[CH2:9][NH:8][C:7]=2[CH:6]=[CH:5][CH:4]=1.N1C=CC=CC=1.[F:21][C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][C:23]=1[S:28](Cl)(=[O:30])=[O:29]>C(Cl)Cl.Cl>[Br:2][C:3]1[C:12]2[O:11][C:10]([CH3:14])([CH3:13])[CH2:9][N:8]([S:28]([C:23]3[CH:24]=[CH:25][CH:26]=[CH:27][C:22]=3[F:21])(=[O:30])=[O:29])[C:7]=2[CH:6]=[CH:5][CH:4]=1
8-Bromo-2,2-dimethyl-3,4-dihydro-2H-benzo[1,4]oxazine hydrochloride (518 mg, 2.14 mmol) was dissolved in 5 ml methylene chloride, to which pyridine (253.85 g, 3.21 mmol) was then added. The reaction mix was stirred at room temperature, and 2-fluorobenzenesulfonyl chloride (416.37 mg, 2.14 mmol) was added drop-wise to the reaction mix, after which stirring at room temperature was continued for 2 hours. The reaction mix was then heated to reflux for 1 hour, and cooled to room temperature. The reaction mix was diluted with 5 ml of methylene chloride and 10% aqueous HCl was added. The organic layer was separated, washed with water, then saturated NaHCO3, and dried (Na2SO4). Solvent was removed under reduced pressure, and the residue was purified via flash chromatography (EtOAc in hexane, 5% to 20%) to afford 610 g (71.3%) of 8-bromo-4-(2-fluoro-benzenesulfonyl)-2,2-dimethyl-3,4-dihydro-2H-benzo[1,4]oxazine as an oil which solidified upon standing. MP: 108.0–110.1° C. MS: (M+H) 401.
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