The general procedure for the synthesis of methyl 3-pyrrolecarboxylate from 3-pyrrolecarboxylic acid and methanol was as follows: 1H-pyrrole-3-carboxylic acid (4.3 g, 38.7 mmol) was dissolved in methanol (40 mL) and cooled to 0-5 °C. 6N hydrochloric acid (9 mL) was added slowly, keeping the temperature at 0-5 °C. The reaction mixture was stirred at room temperature for 5 minutes and subsequently heated to reflux and kept overnight. Upon completion of the reaction, the mixture was cooled to room temperature and concentrated under reduced pressure to remove most of the solvent. The concentrate was cooled to 0 °C and saturated sodium bicarbonate solution was slowly added to adjust the pH to about 7. The mixture was extracted with ethyl acetate, the organic layers were combined and dried over anhydrous sodium sulfate. The desiccant was removed by filtration and the solvent was evaporated under reduced pressure to give methyl 1H-pyrrole-3-carboxylate as a brown solid (4 g, 83% yield). The product was confirmed by 1HNMR (400 MHz, CDCl3): δ 8.56 (broad single peak, 1H), 7.43 (single peak, 1H), 6.75 (single peak, 1H), 6.65 (single peak, 1H), 3.92 (single peak, 3H).LC-MS analysis: calculated exact mass 125.05, measured value m/z 126.2 [M + H]+.
