Ethyl 2,4-dioxovalerate → 4-Acetyl-3-hydroxy-1H-pyrrol-2(5H)-one

Temperatur

-40 °C

A solution of ethyl 2,4-dioxovalerate (1.13 g, 7.11 mmole), dimethylmethylene ammonium chloride (0.67 g, 7.11 mmole) and acetonitrile (3 ml) was stirred at 25° C. over 45 minutes. The resulting yellow homogeneous solution was then cooled to -40° C. and ammonia gas was bubbled through the mixture over 5 minutes, during which time a yellow solid precipitated out of solution. The stirred mixture was allowed to slowly warm to 5° C. over a period of 1 hour before addition of concentrated ammonium hydroxide (4 ml). After stirring for 1 hour, the mixture was concentrated under reduced pressure, diluted with 3N HCl (6 ml) and extracted with ethyl acetate (50 ml×10). The combined organics were dried over sodium sulfate, filtered and concentrated under reduced pressure to give 0.34 g of the title compound as a yellow amorphous solid. M.P. 178°-180° C. (dec); 1H nmr (250 MHz, DMSO-d6 ) δ 2.42 (s, 3H), 3.78 (s, 2H), 8.87 (s, 1H); Anal. calcd. for C5H7NO3 : C, 51.07; H, 5.00; N, 9.92. Found: C, 51.18; H, 5.23; N, 9.73.

1. customammonia gas was bubbled through the mixture over 5 minutes, during which time a yellow solid
2. customprecipitated out of solution
3. temperatureto slowly warm to 5° C. over a period of 1 hour before addition of concentrated ammonium hydroxide (4 ml)
4. concentrationthe mixture was concentrated under reduced pressure
5. additiondiluted with 3N HCl (6 ml)
6. extractionextracted with ethyl acetate (50 ml×10)
7. dry with materialThe combined organics were dried over sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated under reduced pressure

ORD-Eintrag

ord-a6f5298370ef4bb7aff813ae0185b12d

Quelldatensatz

uspto-grants-1996_04

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05508300