To 1 mL of an ethanol solution containing 65 mg of ethyl(2E)-3-(1-(2-(4-((2,3-dihydro-1,4-benzodioxin-6-ylmethyl)amino)piperidin-1-yl)ethyl)-7-methoxy-2-oxo-1,2-dihydroquinolin-4-yl)acrylate, 0.2 mL of water and 0.11 mL of 5 mol/L aqueous sodium hydroxide solution were added and stirred for 1 hour. 2 mL of water was added, removed ethanol under reduced pressure, adjusted to pH 6.0 with 1 mol/L hydrochloric acid, and the resulting solid was filtered to afford 48 mg of (2E)-3-(1-(2-(4-((2,3-dihydro-1,4-benzodioxin-6-ylmethyl)amino)piperidin-1-yl)ethyl)-7-methoxy-2-oxo-1,2-dihydroquinolin-4-yl)acrylic acid as a yellow solid.
