Sodium Hydroxide → 6-Chloro-7-(4-(4-chloro-2-methoxyphenethylcarbamoyl)phenoxy)chroman-4-carboxylic acid

To a solution of ethyl 6-chloro-7-(4-(4-chloro-2-methoxyphenethylcarbamoyl)phenoxy)chroman-4-carboxylate (31.0 g, 56.9 mmol) in 3:1 THF/EtOH (200 ml) was added sodium hydroxide (120 ml, 120 mmol), and the reaction was allowed to stir overnight at ambient temperature, at which point it was complete as determined by thin layer chromatography. The reaction was concentrated to about 25% volume, taken up in 100 ml of EtOH and 100 ml of water, and acidified with 10 ml of concentrated HCl with stirring. The product initially oiled out, but became a solid. The solids were collected by filtration and washed with 200 ml of water to yield 6-chloro-7-(4-(4-chloro-2-methoxyphenethylcarbamoyl)phenoxy)chroman-4-carboxylic acid (24.7 g, 47.8 mmol) as a white solid.