Boron trifluoride etherate → 5-Butyl-3-(trifluoromethyl)-1H-pyrazole

Temperature

-78 °C

To a solution of 1-Hexyne (3.37 mL, 29.4 mmol) in THF (30 mL) was added n-BuLi (2.78 M, 10.2 mL, 29.4 mmol). The solution was stirred at −78° C. for 30 minutes then CF3CO2Et (3.5 mL, 29.35 mL) and BF3—OEt2 were added successively. The reaction was further stirred at −78° C. for 2 h and was quenched with satd. NH4Cl. It was then warmed up to the room temperature. The THF was removed, the residue taken into ether, washed with saturated brine solution, dried over Na2SO4 and reduced. The crude product was then dissolved in benzene (25 mL) and hydrazine (29.4 mmol) was added. The reaction mixture was refluxed overnight, then cooled, the solvent evaporated, and the residue taken into CH2Cl2 (30 mL), washed with brine, dried over Na2SO4 and concentrated to give the title compound as colorless oil.

1. stirringThe reaction was further stirred at −78° C. for 2 h
2. customwas quenched with satd
3. temperatureIt was then warmed up to the room temperature
4. customThe THF was removed
5. washwashed with saturated brine solution
6. dry with materialdried over Na2SO4
7. dissolutionThe crude product was then dissolved in benzene (25 mL)
8. temperatureThe reaction mixture was refluxed overnight
9. temperaturecooled
10. customthe solvent evaporated
11. washwashed with brine
12. dry with materialdried over Na2SO4
13. concentrationconcentrated

ORD record

ord-69b8ff7fe1144a948e8680c06baac7b1

Source dataset

uspto-grants-2008_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07449576B1