A solution of [3-(2,4-dichlorobenzyl)-4-difluoromethoxy-2-ethyl-8-fluoroquinolin-5-yloxy]acetic acid methyl ester (0.17 g), methanol (6 mL), water (0.3 mL) and 5.0 M aqueous sodium hydroxide solution (0.15 mL) was stirred at room temperature for 1 hour. The pH of the solution was adjusted to 5 by the addition of glacial acetic acid and the solvent removed under reduced pressure. The residue was diluted with water and the solid collected by filtration. Purification by column chromatography on silica gel, eluting with a mixture of dichloromethane and methanol (1:0 to 3:1 by volume) gave title compound as a white solid, 0.030 g.
