反应详情

温度

50 °C

Acetic anhydride (8 mL) was treated with 70% nitric acid (1.6 mL) and the mixture heated to 50° C. for 15 minutes, then cooled to room temperature, and slowly added to a suspension of 1-methyl-2-pyrrolecarboxylic acid (2 g) in Ac2O (12 mL) and cooled to −25° C. The mixture was stirred at −15° C. for 0.5 hr, then the temperature was allowed to rise to ambient, and stirring was continued for 20 min. The mixture was again cooled to −25° C. and the resulting precipitate was collected in a funnel cooled on dry ice. The solid was washed with a small amount of cold Ac2O (−25° C.), and then dissolved in 1M NaOH solution. Acidification with 1M HCl precipitated the compound. Yield (0.77 g, 28%). 1H NMR (DMSO): δ 8.19 (d, 1H, J=1.8 Hz); 7.23 (d, 1H, J=2.0 Hz); 3.90 (s, 3H).

1. temperaturecooled to room temperature
2. temperaturecooled to −25° C
3. stirringstirring
4. waitwas continued for 20 min
5. temperatureThe mixture was again cooled to −25° C.
6. customthe resulting precipitate was collected in a funnel
7. temperaturecooled on dry ice
8. washThe solid was washed with a small amount of cold Ac2O (−25° C.)
9. dissolutiondissolved in 1M NaOH solution
10. customAcidification with 1M HCl precipitated the compound
11. customYield (0.77 g, 28%)