[C:1]([NH:5][C:6]1[CH:12]=[CH:11][C:9](N)=[CH:8][CH:7]=1)(=[O:4])[CH2:2]C.CO.C[N:16]([CH3:19])C=O>>[N:16]1[C:19]2[CH:11]=[CH:9][CH:8]=[CH:7][C:6]=2[NH:5][C:2]=1[C:1]([NH:5][C:6]1[CH:12]=[CH:11][CH:9]=[CH:8][CH:7]=1)=[O:4]14.4 g (0.05 mol) of dibenzimidazo(1,2a,1',2'-d)tetrahydropyrazine-6,13-dione and 30 g (0.18 mol) of 4-propionylaminoaniline are heated under reflux in 70 ml of dry dimethylformamide for 3 hours. After cooling down, about 700 ml of methanol are added. The precipitated solid is filtered off with suction and washed with methanol and dried to leave 20.7 g of the benzimidazole-2-carboxanilide of the formula ##STR93## Melting point 289°-291° C.
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