1-Bromopropane → 3,5-dibromo-1-propyl-4-nitro-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A mixture of 3,5-dibromo-4-nitropyrazole (2) (25 g, 92 mmol) in DMF (120 ml) was added over 45 minutes to a suspension of NaH (4.0 g, 10 mmol; 60% dispersion in oil, prewashed with hexane) in DMF (200 ml) with stirring and under an inert atmosphere. After stirring for 30 minutes, a solution of 1-bromopropane (13.6 g, 111 mmol) in DMF (40 ml) was added over 10 minutes. The reaction mixture was heated at 50-60° C. for 3 hours (monitored by TLC) and the DMF was then evaporated off under reduced pressure. A mixture of DCM/water (300 ml, 1/5) was added and the organic phase was then extracted with water (2×50 ml). The organic phase was dried over Na2SO4 and the solvent was evaporated off under reduced pressure. The crude reaction product was obtained as a black oil (19.4 g, 70%), which was used without further purification in the amination step.

Provenance & Evidence