[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[N:6]([CH:8]=[C:9]([C:11]([CH3:16])([CH3:15])[C:12](O)=[O:13])[N:10]=2)[N:7]=1.[BH4-].C([N+](CCCC)(CCCC)CCCC)CCC.Cl>O1CCCC1>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[N:6]([CH:8]=[C:9]([C:11]([CH3:16])([CH3:15])[CH2:12][OH:13])[N:10]=2)[N:7]=10.719 g of 2-(6-chloroimidazo[1,2-b]pyridazin-2-yl)-2-methylpropionic acid was dissolved in 15 ml of tetrahydrofuran; 0.535 g of N,N′-carbonyldiimidazole was added, followed by stirring at room temperature for 60 minutes. To this mixture, 1.15 g of tetra-n-butylammonium borohydride was added under ice cooling conditions, followed by stirring at room temperature for 1 hour. 2 ml of 5 N hydrochloric acid was added to the reaction mixture, followed by concentration under reduced pressure. The residue was adjusted to pH 7 by the addition of aqueous sodium carbonate and extracted with ethyl acetate; the extract was washed with saline, dried over magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography and eluted with ethyl acetate. The desired fraction was collected and concentrated; the crystal obtained was collected by filtration to yield 0.488 g of the title compound.
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