Methyl 3-chloro-1H-pyrrole-2-carboxylate

872-32-2

226410-00-0

General procedure for the synthesis of methyl 3-chloropyrrole-2-carboxylate from 2-methylpyrroline: 5-methyl-3,4-dihydro-2H-pyrrole (1.00 g, 12.0 mmol) was dissolved in carbon tetrachloride. To this solution was added N-chlorosuccinimide (NCS, 12.85 g, 96 mmol) and the reaction mixture was heated to 85 °C and stirred overnight. After completion of the reaction, the mixture was cooled to 0 °C, the precipitate was collected by filtration and the solvent was removed by evaporation. The residue was dissolved in methanol and sodium methanolate (3.90 g, 72.2 mmol) was added. The resulting suspension was heated to reflux and stirred for 3 hours. Upon completion of the reaction, the methanol was removed by evaporation and the residue was suspended in ether. The solids were removed by filtration and the ether was removed by evaporation. The residue was dissolved in dichloromethane and 2M hydrochloric acid was added. The two-phase solution was stirred until the ingredients were completely consumed. The organic and aqueous phases were separated, the organic phase was dried with anhydrous magnesium sulfate and concentrated by evaporation to give an orange oil. The crude product was purified by silica gel column chromatography using 40 g silica gel with ethyl acetate and hexane as eluents to afford methyl 3-chloropyrrole-2-carboxylate as an orange solid (0.2958 g, 1.854 mmol, 15.41% yield).1H NMR (400 MHz, CDCl3): δ 9.54 (br.s., 1H), 6.80 (s, 1H) , 6.17 (s, 1H), 3.83 (s, 3H).MS: m/z 160.0 (M + 1).