Dimethylformamide → 5-formyl-1-methyl-1H-pyrrole-3-carbonitrile

Temperature

-45 °C

1-Methylpyrrole-2-carbaldehyde (10 g, 91.6 mmol) was dissolved in acetonitrile (100 ml) and cooled to −45° C. Chlorosulfonyl isocyanate (38.9 g, 274.9 mmol) in acetonitrile (40 ml) was added dropwise in the course of 40 minutes. The mixture was subsequently stirred for 12 hours at room temperature. After dropwise addition of dimethylformamide (35 ml), the mixture was warmed to 50° C. for 1 hour. After cooling to room temperature, the reaction mixture was poured onto ice (200 ml) and 2N sodium hydroxide solution (286 ml). The precipitate formed was filtered off with suction. The filtrate was extracted with diethyl ether. The combined ether phases were washed until neutral with dilute sodium hydrogen carbonate solution and water and dried over sodium sulfate. The solvent was distilled out in a water pump vacuum and the residue was combined with the precipitate previously obtained. Recrystallization from petroleum ether gave 4-cyano-1-methylpyrrole-2-carbaldehyde (4.3 g) (see, for example, C. E. Loader et al. Can. J. Chem. (1981), 59, 2673-6) 1-H [sic] NMR (CDCl3) δ=4.0 (s, 3H); 7.2 (s, 1H); 7.3 (s, 1H); 9.6 (s, 1H).

1. temperaturethe mixture was warmed to 50° C. for 1 hour
2. temperatureAfter cooling to room temperature
3. customThe precipitate formed
4. filtrationwas filtered off with suction
5. extractionThe filtrate was extracted with diethyl ether
6. washThe combined ether phases were washed until neutral with dilute sodium hydrogen carbonate solution and water
7. dry with materialdried over sodium sulfate
8. distillationThe solvent was distilled out in a water pump vacuum
9. custompreviously obtained
10. customRecrystallization from petroleum ether

ORD record

ord-9b48a5b191fd4f6eb39692d6b647934a

Source dataset

uspto-grants-2004_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06740647B1