[Br:1][C:2]1[CH:3]=[C:4]([N:8]2[C:12]3[CH:13]=[CH:14][C:15]([C:17](=O)[CH3:18])=[CH:16][C:11]=3[N:10]=[CH:9]2)[CH:5]=[CH:6][CH:7]=1.[CH:20]([NH2:22])=[O:21].C(O)=O>>[Br:1][C:2]1[CH:3]=[C:4]([N:8]2[C:12]3[CH:13]=[CH:14][C:15]([CH:17]([NH:22][CH:20]=[O:21])[CH3:18])=[CH:16][C:11]=3[N:10]=[CH:9]2)[CH:5]=[CH:6][CH:7]=1A mixture of 1-[1-(3-bromo-phenyl)-1H-benzoimidazol-5-yl]-ethanone (7.5 g, 23.8 mmol), formamide (9.5 ml, 23.8 mmol) and formic acid (22.4 ml, 595 mmol) was stirred at 190° C. for 7 hours. The cooled mixture was decanted. The residue was rendered alkaline by addition of saturated, aqueous sodium carbonate and extracted with ethyl acetate. The organic extract was dried over magnesium sulphate and concentrated in vacuo. The concentrate was eluted through silica gel with a mixture of dichloromethane, methanol and aqueous ammonia (9:1:0.1 v/v/v) to afford the desired product (60%).
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