[F:1][C:2]1[C:3]([C:9]2[C:13]([CH3:14])=[C:12]([C:15]([O:17]C)=[O:16])[N:11]([CH3:19])[N:10]=2)=[N:4][CH:5]=[C:6]([Cl:8])[CH:7]=1.[OH-].[Na+].Cl>CS(C)=O>[F:1][C:2]1[C:3]([C:9]2[C:13]([CH3:14])=[C:12]([C:15]([OH:17])=[O:16])[N:11]([CH3:19])[N:10]=2)=[N:4][CH:5]=[C:6]([Cl:8])[CH:7]=16.75 g of 3-(3-fluoro-5-chloro-2-pyridyl)-4-methyl-5methoxycarbonyl-1-methyl-[1H]-pyrazole are suspended in 40 ml of dimethyl sulfoxide. 14.3 ml of a 2 molar sodium hydroxide solution are added dropwise, while cooling occasionally in an ice-bath (temperature <30° C.). The thick yellow-brown suspension is stirred at 22° C. for 2 hours. The resulting suspension is then introduced into ice-water and the pH is brought to 1 with 2 molar hydrochloric acid. The slurry formed is filtered with suction and the solid is washed thoroughly with cold water and then dried in vacuo at 60° C. 5.97 g of the desired title compound are obtained as a beige solid of melting point 194-196° C.
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