[NH2:1][C:2]1[C:10]([Br:11])=[C:9]([C:12]([O:14][CH3:15])=[O:13])[C:8]([Br:16])=[CH:7][C:3]=1C(O)=O.C([N:19]([CH2:22]C)CC)C.C1(P(N=[N+]=[N-])(C2C=CC=CC=2)=[O:31])C=CC=CC=1.Cl>O1CCOCC1.O.C(OCC)(=O)C>[Br:11][C:10]1[C:2]2[NH:1][C:22](=[O:31])[NH:19][C:3]=2[CH:7]=[C:8]([Br:16])[C:9]=1[C:12]([O:14][CH3:15])=[O:13]In 10 ml of dioxane is added 1.00 g of 2-amino-3,5-dibromo-4-(methoxycarbonyl)benzoic acid, to which are successively added 0.6 ml of triethylamine and 0.9 ml of diphenyl phosphoryl azide. The mixture thus obtained is heated under reflux for 1.5 hours. Ethyl acetate and water are added to the reaction mixture, pH is adjusted to 6 with 6 mol/L hydrochloric acid, and the organic layer is separated. The organic layer thus obtained is washed with water and saturated aqueous solution of sodium chloride successively and dried over anhydrous magnesium sulfate, and then the solvent is distilled off under reduced pressure. Thus, 0.96 g of methyl 4,6-dibromo-2-oxo-2,3-dihydro-1H-benzimidazole-5-carboxylate is obtained as a light brown-colored solid product.
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