O=S(Cl)Cl.[Br:5][C:6]1[CH:14]=[C:13]([O:15][CH3:16])[CH:12]=[CH:11][C:7]=1[C:8]([OH:10])=[O:9].[CH3:17]O>O>[Br:5][C:6]1[CH:14]=[C:13]([O:15][CH3:16])[CH:12]=[CH:11][C:7]=1[C:8]([O:10][CH3:17])=[O:9]SOCl2 (7.5 mL, 103.0 mmol) is added dropwise to a stirred 0° C. suspension of 2-bromo-4-methoxybenzoic acid (3) (6.5 g, 28.1 mmol) in methanol (12 mL). The mixture is next stirred at 79° C. for 18 h and then cooled to room temperature before removal of methanol and excess SOCl2 at reduced pressure. The residue is diluted with H2O (50 mL) and extracted with ethyl acetate (100 mL and 70 mL). The extract is washed (2 N NaOH and brine) and dried. After solvent removal at reduced pressure, the residue is purified on silica gel (14.3% to 16.7% ethyl acetate/hexane) to give 5.9 g (85%) of 4 as a colorless liquid. IR 2952, 1728, 1597, 1261 cm−1; 1H NMR (CDCl3) δ 3.83 (s, 3H, CH3O), 3.89 (s, 3H, CO2CH3), 6.86 (dd, J=7.2, 2.0 Hz, 1H, 5-PhH), 7.18 (d, J=2.0 Hz, 1H, 3-PhH), 7.85 ppm (d, J=7.2 Hz, 1H, 6-PhH).
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