Cl.[NH2:2][C:3]1[CH:8]=[CH:7][C:6]([C:9]2[N:10]=[CH:11][C:12](=[O:15])[NH:13][CH:14]=2)=[CH:5][CH:4]=1.C(N(CC)CC)C.C(N)(=O)CC.[NH:28]1[CH:33]=[CH:32]N=C[C:29]1=[O:34]>CN(C)C=O>[CH2:14]([N:13]=[C:12]=[O:15])[CH3:9].[CH2:33]([NH:28][C:29](=[O:34])[NH:2][C:3]1[CH:4]=[CH:5][C:6]([C:9]2[N:10]=[CH:11][C:12](=[O:15])[NH:13][CH:14]=2)=[CH:7][CH:8]=1)[CH3:32]5-(4-Aminophenyl)-2(1H)-pyrazinone hydrochloride (1.5 g) was suspended in dimethylformamide (20 ml) and triethylamine (3 ml) was added. The dark solution was filtered. Ethyl isocyanate (0.53 ml) was prepared by slowly adding lead tetra acetate (7.3 g) to a solution of propionamide (1.2 g) in dimethylformamide (50 ml). The solution was initially blood-red, but after stirring for one hour at room temperature it turned colourless. The solution of pyrazinone was added and the mixture stirred at room temperature for 36 hours. It was evaporated to dryness and the residue was washed with water; the resulting orange solid was collected by filtration. Recrystallization from glacial acetic acid afforded the title compound; m.p. >300° C.; νmax (liquid paraffin) 1660, 1640 cm-1 ; δ (DMSO-d6) 1.07 (t, 3H, CH3), 6.05 (t, 1H, --NHEt), 7.93, 8.08 (2d, 2H, pyridine H's).
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