[Br:1][C:2]1[CH:3]=[C:4]([CH:14]=[CH:15][C:16]=1[F:17])[C:5]([C:7]1[C:12]([OH:13])=[CH:11][CH:10]=[CH:9][N:8]=1)=O.Cl.[C:19]([O:23][NH2:24])([CH3:22])([CH3:21])[CH3:20]>C(O)(=O)C>[Br:1][C:2]1[CH:3]=[C:4]([CH:14]=[CH:15][C:16]=1[F:17])/[C:5](/[C:7]1[C:12]([OH:13])=[CH:11][CH:10]=[CH:9][N:8]=1)=[N:24]\[O:23][C:19]([CH3:22])([CH3:21])[CH3:20].[Br:1][C:2]1[CH:3]=[C:4]([CH:14]=[CH:15][C:16]=1[F:17])/[C:5](/[C:7]1[C:12]([OH:13])=[CH:11][CH:10]=[CH:9][N:8]=1)=[N:24]/[O:23][C:19]([CH3:22])([CH3:21])[CH3:20]A mixture of 2-(3-bromo-4-fluorobenzoyl)-3-hydroxypyridine (2.96 g), O-t-butyl hydroxylamine hydrochloride (1.88 g) and acetic acid (50 mL) was stirred at 90° C. for 14 hours. The reaction mixture was concentrated in vacuo, which was subjected to addition with ethyl acetate and water. The ethyl acetate solution was washed with aqueous NaHCO3 and a saturated aqueous saline solution, successively, which was dried (magnesium sulfate), followed by distilling off the solvent under reduced pressure. The residue was subjected to purification by means of a silica gel column (ethyl acetate--hexane) to afford (E)-2-(3-bromo-α-t-butoxyimino-4-fluorobenzyl)-3-hydroxypyridine (1.10 g) and (Z)-2-(3-bromo-α-t-butoxyimino-4-fluorobenzyl)-3-hydroxypyridine (1.97 g) (compounds 17 and 16).
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