methyl 2-methyl-5-morpholino-3-(naphthalen-1-ylmethyl)-3H-imidazo[4,5-b]pyridine-7-carboxylate → 2-methyl-5-morpholino-3-(naphthalen-1-ylmethyl)-3H-imidazo[4,5-b]pyridine-7-carboxylic acid

A mixture of methyl 2-methyl-5-morpholino-3-(naphthalen-1-ylmethyl)-3H-imidazo[4,5-b]pyridine-7-carboxylate (134 mg, 0.32 mmol) in 2N LiOH (15 mL) and THF (15 mL) was stirred at 50° C. for 5 h. It was cooled to room temperature and the precipitate was collected by filtration. It was then poured into water (100 mL) and the suspension was acidified with formic acid to pH=1. It was filtered and the solid was purified by chromatography on silica gel eluted with MeOH/DCM=1/5 to afford the crude product. It was then made a further purification by prep-HPLC to afford the desired product as a yellow solid (64 mg, 50%); LC/MS: MS (ES+) m/e 403 (MH+); 1H NMR (300 MHz, DMSO-d6) δ ppm 2.63 (s, 3H), 3.48 (t, J=4.2 Hz, 4H), 3.65 (t, J=4.2 Hz, 4H), 6.03 (s, 2H), 6.97 (d, J=7.8 Hz, 1H), 7.28 (s, 1H), 7.42 (t, J=7.5 Hz, 1H), 7.58-7.67 (m, 2H), 7.91 (d, J=7.8 Hz, 1H), 8.01 (d, J=7.8 Hz, 1H), 8.33 (d, J=7.8 Hz, 1H).