To a solution of N-benzo[1,3]dioxol-5-ylmethyl-isophthalamic acid (3.0 g, 10 mmol) in methylene chloride was added 1-hydroxy-benzotriazole monohydrate (“HOBt”) (1.35 g, 10 mmol) and ethyl N-benzylglycine (1.94 g, 10 mmol). To this was added 1-(3-dimethylamino-propyl)-3-ethylcarbodiimide hydrochloride (“EDAC”) (1.92 g, 10 mmol) and the mix stirred at room temperature for 24 hours. The solution treated with water (150 mL) and the organic phase separated, washed with 10% citric acid (100 mL), saturated sodium bicarbonate (100 mL) and brine (100 mL). The organic phase dried over magnesium sulfate and evaporated at reduced pressure to give ({3-[(1,3-benzodioxol-5-ylmethyl)-carbamoyl]-benzoyl}-benzyl-amino)-acetic acid ethyl ester as a solid, 3.69 g. To a solution of this ester (3.6 g, 7.6 mmol) in a mix of water (15 mL), dioxane (60 mL) and ethanol (20 mL) was added sodium hydroxide (0.72 g, 18 mmol). The mixture stirred at 50° C. for 24 hours. The solution cooled to room temperature and evaporated at reduced pressure free of solvents. The residue was diluted with water (100 mL) and washed with ether (2×50 mL). The ether discarded and the aqueous phase made acidic with 6N HCl. This was extracted with ethyl acetate (2×100 mL). The organic phases washed with brine (100 mL) and dried over magnesium sulfate. The solvent was evaporated at reduced pressure to give the title compound, 3.41 g. Microanalysis (C25H22N2O6.0.3H2O): Calc'd: C=66.45; H=5.05; N=6.20. Found: C=66.25; H=5.15; N=5.99.
