Lithium Hydroxide → 4-(2-Methylpiperidin-1-YL)-3-(trifluoromethyl)benzoic acid

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Reaction Steps

To a stirred solution of methyl 4-(2-methylpiperidin-1-yl)-3-(trifluoromethyl)benzoate obtained in step 2 (6.6 g, 21.9 mmol) in THF (50 mL) and water (5 mL) was added lithium hydroxide (1.84 g, 43.8 mmol). The resulting mixture was stirred at RT for 12 h. Solvents were removed under vacuum and the resulting mass was diluted with water. The aqueous layer was washed with DCM (2×50 mL) and was acidified with conc HCl (pH=4). It was extracted with EtOAc (2×100 mL). The EtOAc layer was washed with brine and dried over sodium sulfate, affording the title compound as a white solid. 1H NMR (DMSO-d6, 400 MHz) δ 13.30 (bs, 1H), 8.15-8.19 (m, 2H), 7.67-7.70 (d, 1H), 3.08 (m, 1H), 2.86-2.89 (m, 1H), 2.49-2.50 (m, 1H), 1.89-1.90 (m, 2H), 1.74-1.76 (m, 2H), 1.43-1.46 (m, 1H), 1.40-1.41 (m, 1H), 0.77 (d, 3H). LC/MS (Method A): 288.1 (M+H)+. HPLC (Method B) Rt 3.71 min (Purity: 98.3%).

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