In a reaction flask, a stirred solution of acetic acid (2.5 mL) of the compound (CAS: 35490-05-2, 0.11 g, 0.55 mmol) was added, followed by manganese triacetate dihydrate (8 mg, 0.028 mmol) and cobalt chloride (12 mg, 0.011 mmol). The reaction mixture was stirred vigorously at 25 °C for 3 h. Ammonium acetate (0.42 g, 5.5 mmol) was then added. The reaction system was heated to 60 °C and maintained for 30 min, after which it was cooled to room temperature. The solvent was removed by distillation under reduced pressure and the resulting crude product was purified by fast column chromatography on silica gel to afford ethyl 5-methyl-1H-pyrrole-2-carboxylate (54 mg, 0.35 mmol, 64% yield) as a white solid.
