[C:1]([C:4]1[CH:5]=[C:6]([CH:11]=[C:12]([Br:14])[CH:13]=1)[C:7]([O:9]C)=[O:8])(=O)[CH3:2].[OH-].[K+].O.NN.Cl>C(O)CO.O>[Br:14][C:12]1[CH:11]=[C:6]([CH:5]=[C:4]([CH2:1][CH3:2])[CH:13]=1)[C:7]([OH:9])=[O:8]The compound methyl 3-acetyl-5-bromobenzoate (1.2 g, 4.8 mmol) was dissolved in ethylene glycol (10 mL) and KOH (0.41 g, 7.3 mmol) followed by hydrazine hydrate (0.44 mL, 7.3 mmol) were added. The reaction mixture was heated to 200° C. for 1 h. The reaction mixture was cooled to room temperature and diluted with water. The pH of the aqueous layer was adjusted to 2-3 using 1.5N HCl. The product was extracted with EtOAc. The organic layer was washed with water and brine and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure. The crude product was purified by column chromatography (silica 60-120 mesh, eluent 50% EtOAc in petroleum ether) to yield 3-bromo-5-ethylbenzoic acid (0.95 g, yield 89%) as a yellow solid. 1H NMR (300 MHz, CDCl3) δ 8.07 (m, 1H), 7.88 (m, 1H), 7.59 (m, 1H), 2.73 (q, J=7.6 Hz, 2H), 1.28 (t, J=7.6 Hz, 3H). MS (ESI) m/z: Calculated for C9H9BrO2: 227.98. found: 229.0 (M+H)+.
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