Tetrahydrofuran → 2-{[3-cyclopentyl-1-(2-methylphenyl)-1H-pyrazol-5-yl]amino}benzoic acid

To a solution of methyl 2-{[3-cyclopentyl-1-(2-methylphenyl)-1H-pyrazol-5-yl]amino}benzoate (0.59 mmol, 220 mg) in MeOH (1.8 mL) was added THF (5.4 mL) and 1N aqueous NaOH (1.8 mL). The reaction was stirred at rt for 21 h. The organic solvents were removed under reduced pressure, the residue was diluted with water, and the aqueous solution extracted with diethylether (2×5 mL). The aqueous layer was acidified to pH=1 to 2 with 1N aqueous HCl. The mixture was extracted with ethyl acetate (3×5 mL). After removal of the solvent under reduced pressure, the product was obtained as a white solid (169 mg, 79%). 1H NMR (400 MHz, DMSO-d6) δ 1.58-1.62 (m, 2H), 1.65-1.78 (m, 4H), 1.90-2.01 (m, 2H), 2.06 (s, 3H), 2.99-3.10 (m, 1H), 6.23 (s, 1H), 6.80 (t, 1H), 7.20-7.30 (m, 3H), 7.30-7.40 (m, 2H), 7.42-7.51 (m, 1H), 7.81 (d, 1H), 9.84 (s, 1H), 13.14 (s, 1H). ES-MS m/z 362.3 (MH+), HPLC RT (min) 3.39.