[F:1][C:2]([F:12])([F:11])[C:3]1([CH2:9][OH:10])[CH2:8][CH2:7][CH2:6][CH2:5][CH2:4]1.CC(C)([O-])C.[K+].[Cl:19][C:20]1[C:21](F)=[CH:22][C:23]([F:29])=[C:24]([CH:28]=1)[C:25]([OH:27])=[O:26].Cl>CS(C)=O>[Cl:19][C:20]1[C:21]([O:10][CH2:9][C:3]2([C:2]([F:11])([F:12])[F:1])[CH2:8][CH2:7][CH2:6][CH2:5][CH2:4]2)=[CH:22][C:23]([F:29])=[C:24]([CH:28]=1)[C:25]([OH:27])=[O:26]To a solution of (1-(trifluoromethyl)cyclohexyl)methanol (3.20 g, 17.57 mmol) in anhydrous dimethylsulfoxide (50 ml) was added potassium tert-butoxide (4.90 g, 43.66 mmol) and the reaction mixture was stirred at ambient temperature for 30 minutes. 5-chloro-2,4-difluorobenzoic acid (3.38 g, 17.55 mmol) was added to the reaction mixture, and stirring was continued for 2 hours. The reaction mixture was acidified to pH=1 with 5% aqueous hydrochloric acid solution and extracted with ethyl acetate, the combined organic extracts was washed with brine; dried over anhydrous sodium sulfate and concentrated in vacuo. Purification of the residue by column chromatography (30% ethyl acetate in hexanes) afforded the title compound (5.20 g, 83%) containing o-substituted regioisomer, which was used for next step without further purification: MS (ES−) m/z 355.2, 353.2 (M−1).
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