[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([Cl:8])[C:3]=1[C:9]1[NH:10][C:11]2[CH:17]=[C:16]([C:18]([OH:20])=O)[CH:15]=[CH:14][C:12]=2[N:13]=1.CN(C=O)C.C(Cl)[Cl:27]>S(Cl)(Cl)=O>[ClH:1].[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([Cl:8])[C:3]=1[C:9]1[NH:10][C:11]2[CH:17]=[C:16]([C:18]([Cl:27])=[O:20])[CH:15]=[CH:14][C:12]=2[N:13]=1A mixture of 2-(2,6-dichlorophenyl)-3H-benzoimidazole-5-carboxylic acid (5 g) in thionyl chloride (10 mL) containing a catalytic quantity of DMF was stirred at RT for 18 h. Methylene chloride was added and the resulting solid was filtered, washed with methylene chloride and dried under reduced pressure to give the title compound as an off-white solid.
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