Sodium Hydroxide → 1-(2-Carboxyethyl)-4-phenylpyrrole-2-carboxylic acid

10% Aqueous sodium hydroxide solution (20 mL) was added to a stirred solution of ethyl 1-(3-ethoxy-3-oxo-propyl)-4-phenyl-pyrrole-2-carboxylate (2.0 g, 6.35 mmol) in ethanol (20 mL). The reaction mixture was stirred for 2 h at 50-60° C. The ethanol was evaporated in vacuo and then water added to the residue and acidified with 5N HCl to pH 4-5. The precipitated solid was filtered, washed with water and dried in vacuo to afford 1-(2-carboxyethyl)-4-phenyl-pyrrole-2-carboxylic acid (900 mg, 56%) as a solid.