Ethyl 2-acetylacetoacetate → 2,5,7-Trimethylpyrazolo[1,5-a]pyrimidine-6-carboxylic acid

Temperature

120 °C

3-Amino-5-methylpyrazole (970 mg) and ethyl diacetoacetate (1.7 g) were dissolved in acetic acid (5 ml) and stirred at 120° C. for 3 hours. The reaction mixture was cooled to room temperature and concentrated under reduced pressure. Ethanol (5 ml) and 5 N sodium hydroxide solution (2 ml) were added to the residue and stirred at 70° C. for 1 hour. The reaction mixture was cooled to room temperature, and water was added to the reaction mixture which was then washed with ethyl acetate. 2 N Hydrochloric acid was added to the aqueous phase until it became acidic, and precipitated crystals were collected by filtration and washed with water and n-hexane. The crystals were dried under reduced pressure to give the title compound (1.6 g, Y.:80%) as white crystals.

1. temperatureThe reaction mixture was cooled to room temperature
2. concentrationconcentrated under reduced pressure
3. additionEthanol (5 ml) and 5 N sodium hydroxide solution (2 ml) were added to the residue
4. stirringstirred at 70° C. for 1 hour
5. temperatureThe reaction mixture was cooled to room temperature
6. additionwater was added to the reaction mixture which
7. washwas then washed with ethyl acetate
8. addition2 N Hydrochloric acid was added to the aqueous phase until it
9. customprecipitated crystals
10. filtrationwere collected by filtration
11. washwashed with water and n-hexane
12. customThe crystals were dried under reduced pressure

ORD record

ord-6cf7025ab8cb42209e940a1189cb4adc

Source dataset

uspto-grants-2008_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07345180B2