Hydrochloric Acid → Ethyl 4-tridecylpyrrole-2-carboxylate

After washing 140 mg (3.50 mmol) of 60% sodium hydride with hexane, 20 ml of dimethylformamide was added thereto, and then 90 mg (3.38 mmol) of 4-tridecylpyrrole-2-carboxylic acid prepared in Example 2 was further added portionwise under stirring at room temperature. After stirring for 10 minutes, 5.0 g (31.8 mmol) of ethyl idodide was added to the reaction solution followed by heating it at 55° C. for 22 hours. After cooling, an aqueous solution of hydrochloric acid was added to acidify the mixture, and the resulting mixture was then extracted with ethyl acetate, washed with an aquous saturated solution of sodium chloride and dried over anhydrous magnesium sulfate. After removing the solvent under reduced pressure, the residue was purified by subjecting it to column chromatography over silica gel (eluent: ethyl acetate/hexane=1/10) to obtain 600 mg (55% yield) of ethyl 4-tridecylpyrrole-2-carboxylate as white crystals, m.p. 59°-60° C.