Trifluoroacetic acid → [3-(Methoxycarbonyl)phenoxy]acetic acid

To a solution of 3-tert-butoxycarbonylmethoxy-benzoic acid methyl ester (1.00 g, 3.75 mmol) in methylene chloride (4 mL), add trifluoroacetic acid (0.50 mL, 6.6 mmol). Stir the mixture overnight at room temperature in an open vial to allow the solvent to escape. Add an additional portion of trifluoroacetic acid (0.50 mL, 6.6 mmol) and stir the reaction mixture for an additional 24 hours. Add an additional portion of trifluoroacetic acid (1.50 mL, 19.8 mmol) and stir the reaction at room temperature for 3 days. Concentrate under reduced pressure to provide 0.750 g (95.0%) of 3-carboxymethoxy-benzoic acid methyl ester as a light brown solid.