Tridecanoic acid (102.8 g, 0.48 mol) was dissolved into 480 ml of methylene chloride, and 52.6 ml (0.72 mol) of thionyl chloride and 0.2 ml of N,N-dimethylformamide were added thereto. The mixture was allowed to stand overnight followed by concentration under reduced pressure, and the remaining oil was added to 400 ml of methylene chloride containing 106.6 g (0.8 mol) of anhydrous aluminium chloride. A solution of 50.05 g (0.4 mol) of methyl pyrrole-2-carboxylate in 200 ml of methylene chloride was added dropwise to the mixture for ca. 40 minutes at 3° to 9° C. After the addition was finished, the temperature was raised gradually to room temperature, and the mixture was stirred for 2 hours followed by pouring it into 800 ml of ice water. To this mixture was added 1000 ml of methylene chloride to completely dissolve the crystals. The organic layer was separated, washed with water three times and dried over anhydrous magnesium sulfate. After concentration under reduced pressure, the residue was recrystallized from 400 ml of ethyl acetate and 400 ml of hexane to give 107.2 g (83% yield) of methyl 4-tridecanoylpyrrole-2-carboxylate as white crystals, m.p. 92°-93° C.
