CI.[Br:3][C:4]1[CH:12]=[CH:11][C:7]([C:8]([OH:10])=[O:9])=[C:6]([CH3:13])[CH:5]=1.[C:14](=O)([O-])[O-].[K+].[K+].O>CN(C)C=O>[Br:3][C:4]1[CH:12]=[CH:11][C:7]([C:8]([O:10][CH3:14])=[O:9])=[C:6]([CH3:13])[CH:5]=1Methyl iodide (10.0 mL, 160 mmol) was added to a mixture of 4-bromo-2-methylbenzoic acid (25.0 g, 116 mmol) and potassium carbonate (20.0 g, 145 mmol) in anhydrous dimethylformamide (75 mL) at room temperature under a nitrogen atmosphere and stirred for 18 h. The mixture was poured into water and extracted with ethyl acetate (3×50 mL). The organic phases were combined, washed with copper sulfate solution (50 mL) and brine (50 mL), dried and evaporated. Purification by column chromatography on silica gel using 9:1 hexane/ethyl acetate as eluant provided 21.0 g (79%) of methyl 4-bromo-2-methylbenzoate as a clear liquid: 1H NMR (CDCl3) δ7.85 (d, 1H), 7.42-7.47 (m, 2H), 3.95 (s, 3H), 2.64 (s, 3H); IR (neat) 1726 cm-1 ; Mass spectrum m/z 197, 199 (M+H--OCH3).
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