To a round-bottom flask containing tert-butyl 6-[4-({[6-(3-fluorophenyl)pyridin-3-yl]carbonyl}amino)piperidin-1-yl]nicotinate was added DCM (50 mL) and TFA (18 mL). After stirring at rt overnight the reaction was diluted with toluene (10 mL) and the solvent removed to give 6-[4-({[6-(3-fluorophenyl)pyridin-3-yl]carbonyl}amino)piperidin-1-yl]nicotinic acid, as a white solid (30 mg, 78%). 1H NMR (400 MHz, DMSO-d6) □ ppm 9.06 (1H, s), 8.62 (1H, s), 8.47 (1H, d, J=7.9 Hz), 8.22-8.32 (1H, m), 8.10 (1H, d, J=8.1 Hz), 7.85-8.01 (3H, m), 7.47-7.60 (1H, m), 7.29 (1H, t, J=7.8 Hz), 6.89 (1H, d, J=9.3 Hz), 4.42 (2H, d, J=13.2 Hz), 3.10 (2H, t, J=12.7 Hz), 2.33-2.54 (2H, m), 1.91 (2 h, d, J=13.2 Hz), 1.41-1.63 (2H, m). HRMS (TOF, ES+) calculated: 421.1676; observed 421.1722.
