[C:1]1([C:7]2[C:11]3[CH:12]=[C:13]([C:19]4[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=4)[CH:14]=[C:15]([C:16]([OH:18])=[O:17])[C:10]=3[O:9][CH:8]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.O1CCOCC1.[Br:31]Br>C(Cl)(Cl)Cl>[Br:31][C:8]1[O:9][C:10]2[C:15]([C:16]([OH:18])=[O:17])=[CH:14][C:13]([C:19]3[CH:20]=[CH:21][CH:22]=[CH:23][CH:24]=3)=[CH:12][C:11]=2[C:7]=1[C:1]1[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1A solution of 4.0 g. (0.013 mole) of the product of step D in 50 ml. of dioxane is treated with 2.4 g. of bromine in 450 ml. of chloroform, and the mixture is heated at its reflux temperature overnight. The solution is cooled, washed with water, dried and then evaporated. The residue is triturated with hexane to provide 2-bromo-3,5-diphenylbenzofuran-7-carboxylic acid as a white solid, m.p. 232°-236° C.
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