[CH3:1][O:2][C:3](=[O:21])[C:4]1[CH:9]=[C:8]([CH:10]([OH:12])[CH3:11])[C:7]([C:13]([F:16])([F:15])[F:14])=[CH:6][C:5]=1[NH:17]C(=O)C.O.[C:23]1(C)C=CC(S(O)(=O)=O)=C[CH:24]=1.CCOC(C)=O>CCO>[CH3:1][O:2][C:3](=[O:21])[C:4]1[CH:9]=[C:8]([CH:10]([O:12][CH2:23][CH3:24])[CH3:11])[C:7]([C:13]([F:14])([F:15])[F:16])=[CH:6][C:5]=1[NH2:17]A solution of 2-acetylamino-5-(1-hydroxy-ethyl)-4-trifluoromethyl-benzoic acid methyl ester (500 mg, 1.64 mmol) in EtOH (5 mL) was treated with p-toluenesulfonic acid monohydrate (100 mg, 0.518 mmol) and stirred at r.t. for 5 d. The reaction mixture was taken into EtOAc and washed with sat. aq NaHCO3. The organic phase was dried (Na2SO4), filtered and concentrated in vacuo. The residue was purified by column chromatography (silica gel, 5:1 hexanes/EtOAc) to give title product (270 mg, 57%) as colorless crystals. m.p.: 100-103° C., API-ES: m/z 292 [M+H]+.
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