[Br:1][C:2]1[CH:10]=[CH:9][C:5]([C:6]([OH:8])=[O:7])=[C:4]([CH3:11])[CH:3]=1.S(=O)(=O)(O)O.C(=O)(O)[O-].[Na+].[CH2:22](O)[CH3:23]>>[CH2:22]([O:7][C:6](=[O:8])[C:5]1[CH:9]=[CH:10][C:2]([Br:1])=[CH:3][C:4]=1[CH3:11])[CH3:23]25.3 g of 4-bromo-2-methyl benzoic acid and 5 mL of concentrated sulfuric acid were added to 425 mL of ethanol. The mixture was heated at reflux temperature for 3 days. The solution was cooled to room temperature, adjusted to neutral pH with the addition of sodium bicarbonate, and concentrated to ca. 100 mL volume under reduced pressure. The reduced mixture was partitioned between ethyl acetate and water, and the organic phase was successively washed with saturated bicarbonate and brine solutions. The organic fraction was dried over anhydrous sodium sulfate, and concentrated to 28.2 g of a clear liquid product; 1H NMR (200 MHz, CDCl3) δ 7.78-7.73 (d, J=8.2 Hz, 1H), 7.38-7.32 (m, 2H), 4.40-4.28 (q, J=7 Hz, 2H), 2.57 (s, 3H), 1.42-1.35 (t, J=7 Hz, 3H).
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