[CH:1]1([N:4]2[C:12]([CH3:13])=[C:11]3[C:6]([CH:7]=[CH:8][C:9]([N:14]4[CH:19]=[CH:18][C:17](O)=[CH:16][C:15]4=[O:21])=[CH:10]3)=[N:5]2)[CH2:3][CH2:2]1.P(Cl)(Cl)([Cl:24])=O.C(OCC)(=O)C>CN(C=O)C>[Cl:24][C:17]1[CH:18]=[CH:19][N:14]([C:9]2[CH:8]=[CH:7][C:6]3[C:11](=[C:12]([CH3:13])[N:4]([CH:1]4[CH2:3][CH2:2]4)[N:5]=3)[CH:10]=2)[C:15](=[O:21])[CH:16]=1To a suspension of 1-(2-cyclopropyl-3-methyl-2H-indazol-5-yl)-4-hydroxypyridin-2(1H)-one (118 g) in DMF (2 L) was added phosphorus oxychloride (46.9 ml) at room temperature, and the mixture was stirred under an argon atmosphere at an inside temperature of 45° C. for 22 hr. The reaction mixture was poured into ethyl acetate (3 L), and washed with saturated aqueous sodium hydrogen carbonate (1.5 L). The obtained aqueous layer was extracted twice with ethyl acetate (2 L and 1 L). The organic layer was washed with aqueous sodium sulfite solution and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was dissolved in a 1:1 mixed solvent (1.1 L) of ethyl acetate and tetrahydrofuran with heating, and the mixture was filtered through NH silica gel (750 g). The eluate was concentrated under reduced pressure, and the obtained residue was solidified with diisopropyl ether to give the title compound (73.2 g).
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