4533-42-0

696-59-3

100-01-6

4533-42-0

General procedure: 4-nitroaniline (1 mmol), 2,5-dimethoxytetrahydrofuran (1.1 mmol) and L-(+)-tartaric acid-choline chloride low eutectic solvent (DES, 1.5 g) were added to a 50 mL round-bottomed flask and the reaction mixture was stirred at 90°C. The reaction was carried out by thin-layer chromatography (TLC). The reaction process was monitored by thin layer chromatography (TLC). After completion of the reaction, the mixture was cooled to room temperature and the target product 1-(4-nitrophenyl)-1H-pyrrole was extracted with ethyl acetate. After evaporation of the solvent, the residue was purified by silica gel column chromatography to give the pure product. The low eutectic solvent (DES) was dried under vacuum and reused for the next cycle.