[O-]S([O-])(=O)=O.[Mg+2].OS(O)(=O)=O.[Br:12][C:13]1[CH:21]=[CH:20][C:16]([C:17]([OH:19])=[O:18])=[CH:15][C:14]=1[O:22][CH3:23].[CH3:24][C:25](O)([CH3:27])[CH3:26]>C(Cl)Cl>[Br:12][C:13]1[CH:21]=[CH:20][C:16]([C:17]([O:19][C:25]([CH3:27])([CH3:26])[CH3:24])=[O:18])=[CH:15][C:14]=1[O:22][CH3:23]
MgSO4 (4.82 g, 40.0 mmol), DCM (40 mL), and H2SO4 (533 μL, 10.0 mmol) were combined at 0° C. and the mixture was allowed to stir for 30 minutes at 0° C. 4-Bromo-3-methoxy-benzoic acid (2.31 g, 10.0 mmol) and 2-methylpropan-2-ol (4.78 mL, 50.0 mmol) were added and the mixture was allowed to stir at rt overnight. The mixture was filtered to remove the MgSO4 and the filtrate was washed with 1N NaOH. The layers were separated and the organic layer was dried over sodium sulfate and the solvent was removed to yield 400 mg of tert-butyl 4-bromo-3-methoxybenzoate. ESI-MS m/z calc. 286.0. found 287.0 (M+1)+; Retention time: 3.11 minutes (4 min run).
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