C([O:3][C:4]([C:6]1[S:10][C:9]([C:11]2[CH:12]=[N:13][CH:14]=[CH:15][CH:16]=2)=[N:8][C:7]=1[C:17]([F:20])([F:19])[F:18])=[O:5])C.[OH-].[Na+].Cl.O>CO>[N:13]1[CH:14]=[CH:15][CH:16]=[C:11]([C:9]2[S:10][C:6]([C:4]([OH:5])=[O:3])=[C:7]([C:17]([F:19])([F:20])[F:18])[N:8]=2)[CH:12]=1
To a solution of 2-pyridin-3-yl-4-trifluoromethyl-thiazole-5-carboxylic acid ethyl ester (13.9 g, 46 mmol, ca. 85% pure) in methanol (150 mL) was added an aqueous solution of sodium hydroxide (total volume 75 mL, 140 mmol), and the mixture was stirred for 40 min. Upon addition of 2 N HCl (70 mL, ca pH=3) to the reaction mixture, a precipitate was formed. Water (300 mL) was then added and the heterogeneous mixture was filtered under reduced pressure. The precipitate was rinsed further with water and dried in vacuo to give the desired product as an off-white solid (7.37 g, 58%): mp 209° C.; 1H NMR (300 MHz, DMSO-d6) δ 9.21 (d, J=2.5 Hz, 1H), 8.77 (dd, J=4.9, 1.7 Hz, 1H), 8.41 (dt, J=8.0, 1.7 Hz, 1H), 7.60 (dd, J=8.0, 4.9 Hz, 1H), 3.4 (br s, 1H); ESIMS m/z 276.2 (M+1).
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