C([O:3][C:4](=[O:21])[C:5]1[CH:10]=[CH:9][C:8]([O:11][CH3:12])=[C:7]([O:13][CH2:14][CH2:15][CH2:16][C:17]([F:20])([F:19])[F:18])[CH:6]=1)C.[OH-].[Na+].Cl>C1COCC1>[CH3:12][O:11][C:8]1[CH:9]=[CH:10][C:5]([C:4]([OH:21])=[O:3])=[CH:6][C:7]=1[O:13][CH2:14][CH2:15][CH2:16][C:17]([F:18])([F:20])[F:19]A mixture of 4-methoxy-3-(4,4,4-trifluoro-butoxy)-benzoic acid ethyl ester (0.93 g, 3.04 mmol) in THF (3 mL) and 2N NaOH (2.28 mL, 4.55 mmol) is heated with stirring at 60° C. overnight. After cooling, ice water is added and the pH is adjusted to 1 by addition of HCl 37% to form a white precipitate which is filtered off. The title compound is obtained after drying as white solid. TLC, Rf (hexane/AcOEt 1:1)=0.17. MS: 277.0 [M−H]+. tR (HPLC, Nucleosil C18HD column, 20-100% CH3CN/H2O/6 min, 100% CH3CN/2 min, CH3CN and H2O containing 0.1% TFA, flow: 1 mL/min): 3.90 min. 1H-NMR (CDCl3): δ 1.98 (m, 2H), 2.45 (m, 2H), 3.85 (s, 3H), 4.08 (m, 2H), 7.08 (dd, 1H), 7.46 (d, 1H), 7.60 (dd, 1H), 12.7 (s, br, 1H) ppm.
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