C1(S([NH:10][C:11]([C:13]2[CH:14]=[CH:15][C:16]([N:19](CC3C=C(Br)C=CC=3OCC(C)=C)[CH2:20][CH3:21])=[N:17]C=2)=[O:12])(=O)=O)C=CC=CC=1.C([NH2:37])C>CO>[CH2:20]([NH:19][C:16]1[N:17]=[N:37][C:13]([C:11]([NH2:10])=[O:12])=[CH:14][CH:15]=1)[CH3:21]A suspension of 6-chloropyridazine-3-carboxamide (reference example 13, paragraphs 1 to 3) (28.5 g, 0.18 mol) in methanol (200 ml) was treated with aqueous ethylamine (70% solution, 77 ml). The reaction was heated at reflux for 31/2 hours. The reaction was allowed to cool to ambient temperature and stand overnight. The precipitate was filtered and washed with a small volume of water and dried to give 6-(ethylamino)pyridazine-3-carboxamide as pink solid (8.9 g). [The filtrates were evaporated to a small volume diluted with cold water (100 ml) and more of the desired solid was filtered-off, washed with water and dried (12.8 g). Total yield (21.7 g, 72%)].
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