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5-Phenylpyrrole-2-carboxylate (20 mg, 0.09 mmol) was dissolved in a solvent mixture of 1 mL of tetrahydrofuran, 0.5 mL of methanol and 0.5 mL of water. After stirring at room temperature, LiOH (4 mg, 0.18 mmol) was added. Stirring was continued at room temperature for 2 h. The progress of the reaction was monitored by thin layer chromatography (TLC) and after confirming that the reaction was complete, the solvent was removed using a rotary evaporator. Ice water was added to the reaction residue, which was then acidified with 1 M HCl solution to the appropriate pH and the precipitate was collected by filtration to afford 5-phenyl-1H-pyrrole-2-carboxylic acid (10 mg, 59% yield).

[1] Patent: CN107151255, 2017, A. Location in patent: Paragraph 0244; 0245; 0246
[2] Magnetic Resonance in Chemistry, 2009, vol. 47, # 12, p. 1101 - 1109