[Br:1][C:2]1[CH:3]=[CH:4][C:5]([CH3:11])=[C:6]([CH:10]=1)[C:7]([OH:9])=[O:8].Br[C:13]1C(C)=C(C=CC=1)C(O)=O.CI.C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C>[CH3:13][O:8][C:7](=[O:9])[C:6]1[CH:10]=[C:2]([Br:1])[CH:3]=[CH:4][C:5]=1[CH3:11]A 60:40 mixture of 5-bromo-2-methyl benzoic acid and 3-bromo-2-methyl benzoic acid (8.0 g, 0.037 mol) was dissolved in N,N′-dimethylformamide (130 mL). Methyl iodide (2.28 mL, 2.3 mol) and potassium carbonate (5.11 g, 0.037 mol) were added in sequence at room temperature. The mixture was stirred at room temperature for 2 hours at which point the reaction was determined to be complete by HPLC. The solvent was removed under high vacuum and the resulting residue was passed through a silica gel column using 5% ethyl acetate in hexanes as the eluent. The mixture of isomers was obtained as an oil and then separated by preparative normal phase HPLC using 0.5% isopropyl alcohol in hexanes as the eluent. The title compound was obtained as a white solid (1.38 g, 29%). 1H NMR (300.132 MHz, CDCl3) δ 8.04 (d, J=2.2 Hz, 1H), 7.50 (dd, J=8.2, 2.2 Hz, 1H), 7.12 (d, J=8.2 Hz, 1H), 3.89 (s, 3H), 2.54 (s, 3H).
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