[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH2:8][C:9]([OH:11])=[O:10])=[CH:4][C:3]=1[F:12].[CH3:13]O.S(Cl)(Cl)=O>>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH2:8][C:9]([O:11][CH3:13])=[O:10])=[CH:4][C:3]=1[F:12]To a solution of 2-(4-bromo-3-fluorophenyl)acetic acid (500 mg, 2.146 mmol) in MeOH (10 mL, 247 mmol) was added sulfurous dichloride (0.232 mL, 3.22 mmol). The resulting mixture was stirred at 60° C. After 3 h, LCMS analysis showed the starting material had disappeared and the solvent was removed in vacuo. The residue was dissolved in DCM (60 mL) and washed with aq NaHCO3 (20 mL) and brine (20 mL). The organic layer was dried over Na2SO4, filtered and concentrated to yield a yellow oil of methyl 2-(4-bromo-3-fluorophenyl)acetate (500 mg, 1.774 mmol, 83.0% yield): 1H NMR (400 MHz, CD3OD) δ 7.53 (t, J=8.0 Hz, 1H), 7.15 (dd, J=9.8, 1.7 Hz, 1H), 7.01 (d, J=8.2 Hz, 1H), 3.75-3.61 (m, 5H); ES-LCMS m/z 248.9 (M+H).
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