[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[N:6]([C:8]([CH3:14])=[C:9]([C:11]([OH:13])=O)[N:10]=2)[N:7]=1.Cl.[CH2:16]([O:18][C:19](=[O:22])[CH2:20][NH2:21])[CH3:17].C(N(CC)CC)C>CN(C)C=O>[CH2:16]([O:18][C:19](=[O:22])[CH2:20][NH:21][C:11]([C:9]1[N:10]=[C:5]2[CH:4]=[CH:3][C:2]([Cl:1])=[N:7][N:6]2[C:8]=1[CH3:14])=[O:13])[CH3:17]3.9 g of ethyl 6-chloro-3-methylimidazo[1,2-b]pyridazine-2-carboxylate was suspended in 40 ml of tetrahydrofuran; 30 ml of a 1 N aqueous solution of sodium hydroxide was added, followed by stirring at room temperature for 3 hours. The mixture was concentrated under reduced pressure. The residue was adjusted to pH 4 by the addition of 50 ml of water and 1 N hydrochloric acid; the crystal precipitated was collected by filtration and dried to yield 2.55 g of 6-chloro-3-methylimidazo[1,2-b]pyridazine-2-carboxylic acid. 1.27 g of this carboxylic acid was dissolved in 20 ml of N,N-dimethylformamide; 1.07 g of N,N′-carbonyldiimidazole was added, followed by stirring at room temperature for 30 minutes. To this mixture, 0.922 g of glycine ethyl ester hydrochloride and 0.915 ml of triethylamine were added, followed by further stirring for 3 hours. 60 ml of ice water was added to the reaction mixture; the crystal precipitated was collected by filtration, washed with water and dried to yield 1.18 g of the title compound.
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