Hydrochloric Acid → 1-Methyl-3-(trifluoroMethyl)pyrazole-5-boronic acid

Temperatur

10 °C

A solution of 1-methyl-3-trifluoromethylpyrazol (2 g) in 10 ml THF is cooled under an inert gas atmosphere to −78° C. A 2 M solution of LDA (9.75 ml) is added dropwise. The mixture is stirred to 10° C. for 1 h and cooled to −75° C. Trimethylborate (5.8 ml) is added and after stirring for 1 h at −75° C. the mixture is stirred overnight at ambient temperature. The resulting reaction solution is added to 10% hydrochloric acid (15 ml). The water phase is extracted 3 times with ethyl acetate and the combined organic phases are washed with water and a saturated sodium chloride solution. The organic phase is dried and evaporated and the residue is crystallized from water. After drying, one obtains the title compound as nearly colorless crystals (1.12 g) of mp. 138° C.

1. temperaturecooled to −75° C
2. stirringafter stirring for 1 h at −75° C. the mixture
3. stirringis stirred overnight at ambient temperature
4. customThe resulting reaction solution
5. extractionThe water phase is extracted 3 times with ethyl acetate
6. washthe combined organic phases are washed with water
7. customThe organic phase is dried
8. customevaporated
9. customthe residue is crystallized from water
10. customAfter drying

ORD-Eintrag

ord-b8b9c20b18d141b49324d4ebe17d2e8e

Quelldatensatz

uspto-grants-2003_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06528456B2