反应详情

Acetic anhydride (8 ml) and nitric acid (70%, 1.6 mL) were heated to 50° C. for 15 minutes and cooled to room temperature. The solution was then slowly added to a suspension of 1-methyl-2-pyrrolecarboxylic acid (2.0 g, 0.02 mol) in Ac2O (12 ml) cooled to −25° C. The mixture was stirred for 30 min at −15° C., warmed to room temperature and stirred for another 20 min. The mixture was again cooled to −25° C. and the resulting precipitate collected in a funnel cooled with dry ice. The solid was washed with cold Ac2O (−25° C.), followed by Ac2O:CCl4 (1:1, −25° C.), and then CCl4 and hexane. The yellow solid was dissolved in NaOH (1M) and acidified with HCl to yield the product as a light cream solid which was collected and air-dried. Yield 0.98 g (36%). 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 −25° C
2. temperaturewarmed to room temperature
3. stirringstirred for another 20 min
4. temperatureThe mixture was again cooled to −25° C.
5. customthe resulting precipitate collected in a funnel
6. temperaturecooled with dry ice
7. washThe solid was washed with cold Ac2O (−25° C.)
8. customfollowed by Ac2O:CCl4 (1:1, −25° C.)
9. dissolutionThe yellow solid was dissolved in NaOH (1M)