[CH3:1][O:2][C:3](=[O:19])[C:4]1[CH:13]=[C:12]([O:14][CH:15]([CH3:17])[CH3:16])[CH:11]=[C:6]([C:7]([O:9][CH3:10])=[O:8])[C:5]=1[CH3:18].C1C(=O)N([Br:27])C(=O)C1.CC(N=NC(C#N)(C)C)(C#N)C>C(Cl)(Cl)(Cl)Cl>[CH3:10][O:9][C:7](=[O:8])[C:6]1[CH:11]=[C:12]([O:14][CH:15]([CH3:16])[CH3:17])[CH:13]=[C:4]([C:3]([O:2][CH3:1])=[O:19])[C:5]=1[CH2:18][Br:27]To a solution of 5-isopropoxy-2-methyl-isophthalic acid dimethyl ester (Cpd B, 14.5 g, 54.5 mmol) in CCl4 (250 mL) was added NBS (11.2 g, 60.0 mmol). After stirring the mixture at 85° C. for 5 minutes, AIBN (2.69 g, 16.4 mmol) was added. The resulting reaction mixture was stirred at 85° C. for 1 hour. The reaction mixture was chilled in an ice bath and the precipitates were filtered and discarded. The resulting filtrate was concentrated under vacuum and purified by column chromatography (0-40%, EtOAc/heptanes) to give 2-bromomethyl-5-isopropoxy-isophthalic acid dimethyl ester (Cpd C, 17.5 g, 93% yield) as a clear oil which solidified upon standing.
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