[CH3:1][O:2][C:3]1[C:8]2[CH:9]=[N:10][S:11][C:7]=2[CH:6]=[CH:5][CH:4]=1.[Br:12]Br.C([O-])(O)=O.[Na+].ClCCl>C(Cl)(Cl)(Cl)Cl>[Br:12][C:6]1[C:7]2[S:11][N:10]=[CH:9][C:8]=2[C:3]([O:2][CH3:1])=[CH:4][CH:5]=1
To a solution of 4-methoxy-benzo[d]isothiazole (prepared as described above) (1.0 g, 6.05 mmol) in carbon tetrachloride (20 mL) at 0° C. was added bromine (310 μL, 6.05 mmol) in carbon tetrachloride (10 mL). The reaction was allowed to stir at 0° C. for 3 h and was then warmed to rt. Saturated aqueous NaHCO3 and dichloromethane were added and the organic phase was separated. The aqueous phase was extracted with 2×20 mL dichloromethane. The combined organic phases were dried (MgSO4) and concentrated in vacuo. The residue was purified by flash chromatography eluting silica gel with EtOAc:hexane [0:100 to 1:20] to yield the title compound (980 mg, 66%): δH (300 MHz, CDCl3): 9.09 (1H, s), 7.52 (1H, d, J=8.1 Hz), 6.67 (1H, d, J=8.4 Hz), 4.00 (3H, s).
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