[CH:1]1([O:6][C:7]2[CH:8]=[C:9]([CH:14]=[CH:15][C:16]=2[S:17][CH3:18])[C:10]([O:12]C)=[O:11])[CH2:5][CH2:4][CH2:3][CH2:2]1.[OH-].[Na+].C(O)(=O)C>O.C(O)C>[CH:1]1([O:6][C:7]2[CH:8]=[C:9]([CH:14]=[CH:15][C:16]=2[S:17][CH3:18])[C:10]([OH:12])=[O:11])[CH2:2][CH2:3][CH2:4][CH2:5]1A solution of methyl 3-cyclopentyloxy-4-(methylthio)benzoate (24.3 g, 91.4 mmol) in water (200 mL) and ethanol (50 mL) containing sodium hydroxide (18.3 g, 460 mmol) is heated under reflux for 3 hours. The solution is then poured into water (750 mL) and 1 N acetic acid is added dropwise with stirring to between pH 5-6. The solid which separates is collected by filtration, washed with water (4×100 mL) and dried giving 3-cyclopentyloxy-4-(methylthio)benzoic acid (21.1 g, 91.7%) as a cream solid m.p. 158°-160° C. [Elemental analysis: C,61.5; H,6.31%; calculated: C,61.88; H,6 39%]
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