A 16 mL vial flask was successively charged with (2E)-3-(7-oxo-5,6,7,8-tetrahydro-1,8-naphthyridin-3-yl)acrylic acid hydrochloride (50 mg, 0.20 mmol), DMF (4.8 mL), HOBt (32 mg, 0.23 mmol), DIPEA (78 μL, 0.47 mmol), 4-piperidineethanol (30 mg, 0.23 mmol) and EDAC (45 mg, 0.23 mmol). The reaction mixture was stirred at room temperature overnight and concentrated to dryness. The residue was purified on column chromatography (eluent: dichloromethane/MeOH, 95/5) to give a white solid. This solid was triturated in MeOH, filtered, washed with MeOH and diethyl ether and dried to give the title compound (35 mg, 55%) as a white solid.
