Hydrogen Bromide → 1-(4,5-Diaminopyrazol-1-yl)propan-2-ol hydrobromide

Participants

Reaction Steps

A mixture of 1-(5-benzylamino-3-bromo-4-nitropyrazol-1-yl)propan-2-ol (4-3) (5.0 g; 14.0 mmol) in EtOH (140 ml) containing 10% Pd/C as catalyst (Engelhard, 50% wet, 0.5 g dry weight) and NaOH (solid, 560 mg, 14 mmol) was hydrogenated in an autoclave (1 l) at 11 bar for 2 hours. The reaction mixture was filtered to remove the catalyst, under an inert atmosphere in an ethanolic solution containing HBr (47%, 9.7 ml, 78 mmol). The solvent was evaporated off under reduced pressure to give a solid. After washing with cold EtOH, the 1-(4,5-diaminopyrazol-1-yl)propan-2-ol was obtained in the form of the hydrobromide (3.47 eq HBr) as a white solid (2.3 g, 42%).

Provenance & Evidence