[N:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[C:7]1[C:11]([C:12]([F:15])([F:14])[F:13])=[C:10]([C:16]([O:18]CC)=[O:17])[O:9][N:8]=1.O.[OH-].[Li+].Cl>CO.O>[N:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[C:7]1[C:11]([C:12]([F:14])([F:15])[F:13])=[C:10]([C:16]([OH:18])=[O:17])[O:9][N:8]=1
To a solution of ethyl 3-(pyridin-2-yl)-4-(trifluoromethyl)isoxazole-5-carboxylate (511 mg, 1.79 mmol) in methanol (12 mL) and water (3 mL) at room temperature was added lithium hydroxide, hydrate (74.9 mg, 1.79 mmol). The reaction mixture was stirred for 1 hr. A 1N aqueous solution of hydrochloric acid (1.8 mL) was added, and the solvent were removed under reduced pressure to afford 3-(pyridin-2-yl)-4-(trifluoromethyl)isoxazole-5-carboxylic acid+1LiCl (531 mg, 1.767 mmol, 99% yield) as a white solid. The compound had an HPLC ret. time=0.725 min.-Column: CHROMOLITH® SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.1% TFA; Solvent B=90% MeOH, 10% H2O, 0.1% TFA. LC/MS M+1=258.8. 1H NMR (400 MHz, CD3OD) δ ppm 7.59 (dd, J=7.03, 5.02 Hz, 1H), 7.82 (d, J=7.78 Hz, 1H), 8.01 (td, J=7.78, 1.76 Hz, 1H), and 8.73 (d, 1H).
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