Methyl-1H-pyrrole-2-carboxylate (10 g, 79.9 mmol) was dissolved in anhydrous THF (200 mL) at 0 °C and NaH (3.52 g, 60% w/w, 87.9 mmol) was slowly added. The reaction mixture was stirred at 20 °C for 30 min before CH3I (13.62 g, 95.9 mmol) was added dropwise. The reaction was continued to be stirred at 20 °C for 17 hours. After completion of the reaction, the reaction was quenched by slowly pouring the mixture into aqueous NH4Cl (200 mL). The aqueous phase was extracted with EtOAc (200 mL x 2), the organic layers were combined and washed with brine (150 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: EtOAc/petroleum ether=1/20) to afford methyl 1-methyl-1H-pyrrole-2-carboxylate (9.88 g, 71 mmol, 89% yield) as a yellow oil. Mass spectrum (EI+, m/z): 140.1 [M+H]+.
