反应详情

温度

-7.5 °C

Acetic acid (360 mL) and water (300 ml) was added to a solution of ethyl 3,5-dimethyl-2-pyrrolecarboxylate (5 g, 29.9 mmol) in THF (300 ML). The mixture was cooled to −10 to −5° C. for 30 minutes. To the mixture was then added ceric ammonium nitrate (CAN, 67.21 g, 122.6 mmol) over a period of 30 minutes. The mixture was stirred at −10 to −5° C. for 1.5 hours. The reaction was diluted with water (800 mL) and extracted with dichloromethane (3×). The combined extracts were washed with sodium bicarbonate solution until the aqueous layer was basic, dried and concentrated. The residue was purified on a silica gel column (10% EtOAc in hexane) to give 2.4 g (44%) of 5-formyl-3-methyl-1H-pyrrole-2-carboxylic acid ethyl ester as a white solid. 1H NMR (300 MHz, DMSO-d6) δ 12.61 (br s, 1H, NH), 9.64 (s, 1H, CHO), 6.78 (s, 1H), 4.27 (q, J=7.17 Hz, 2H, OCH2CH3), 2.26 (s, 3H, CH3), 1.30 (t, J=7.17 Hz, 3H, OCH2CH3). MS 182 [M++1].

1. extractionextracted with dichloromethane (3×)
2. washThe combined extracts were washed with sodium bicarbonate solution until the aqueous layer
3. customdried
4. concentrationconcentrated
5. customThe residue was purified on a silica gel column (10% EtOAc in hexane)