C([O:3][C:4](=[O:26])[CH:5]([C:12]1[CH:17]=[CH:16][C:15]([S:18]([CH3:21])(=[O:20])=[O:19])=[C:14]([C:22]([F:25])([F:24])[F:23])[CH:13]=1)[CH2:6][CH:7]1[CH2:11][CH2:10][CH2:9][CH2:8]1)C.[OH-].[Li+]>O1CCCC1.O>[CH:7]1([CH2:6][CH:5]([C:12]2[CH:17]=[CH:16][C:15]([S:18]([CH3:21])(=[O:20])=[O:19])=[C:14]([C:22]([F:25])([F:23])[F:24])[CH:13]=2)[C:4]([OH:26])=[O:3])[CH2:11][CH2:10][CH2:9][CH2:8]1A solution of 3-cyclopentyl-2-(4-methanesulfonyl-3-trifluoromethyl-phenyl)-propionic acid ethyl ester (707 mg, 1.80 mmol in tetrahydrofuran/water (24 mL, 3:1) was treated with lithium hydroxide (166 mg, 3.97 mmol). The reaction was stirred at 25° C. for 24 h. At this time, the reaction concentrated in vacuo. The residue was diluted with water (25 mL) and extracted with diethyl ether (1×15 mL). The aqueous layer was acidified to pH=1 with a 2N aqueous hydrochloric acid solution, and extracted with chloroform (3×25 mL). The combined organic layers were washed with water (1×25 mL) and a saturated aqueous sodium chloride solution (3×25 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to afford 3-cyclopentyl-2-(4-methanesulfonyl-3-trifluoromethyl-phenyl)-propionic acid (426.7 mg, 65%) as a white solid: mp 122-123° C.; EI-HRMS m/e calcd for C16H19F3O4S (M+) 364.0956 found 364.0956.
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