[CH2:1]([O:3][C:4]1[C:5]([CH3:15])=[CH:6][CH:7]=[C:8]([CH:14]=1)[C:9]([O:11][CH2:12][CH3:13])=[O:10])[CH3:2].[Br:16]Br>C(O)(=O)C.O>[Br:16][C:7]1[CH:6]=[C:5]([CH3:15])[C:4]([O:3][CH2:1][CH3:2])=[CH:14][C:8]=1[C:9]([O:11][CH2:12][CH3:13])=[O:10]To a solution of ethyl 5-ethoxy-4-methylbenzoate (500 mg, 2.40 mmol) in acetic acid (10 mL) and water (10 mL) at room temperature was added bromine (385 mg, 2.40 mmol). The resulting reaction mixture was stirred at 60° C. for 1 hour. After cooling to room temperature, the reaction mixture was diluted with hexanes/ether (80/20). Layers were separated and the organic layer was washed with saturated Na2CO3, brine, dried over Na2SO4, filtered and concentrated. The residue was purified on a silica gel column eluting with 5 to 10% EtOAc in hexanes to yield the title intermediate (660 mg, 2.23 mmol) as light yellow solid.
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