Methylhydrazine → 5-(4-Bromophenyl)-1-methyl-1H-pyrazole

Participants

Reaction Steps

A N,N′-dimethylformamide (15 mL) solution of 4-bromoacetophenone (10.60 g, 53.25 mmols) and N,N′-dimethylformamide dimethyl acetal (2.5 equivalents) was heated at 125 degrees Celcius for 3 hours. The dark red solution was cooled to room temperature. The volatiles were removed by rotary evaporation providing a red viscous oil. To this substance was added anhydrous N,N′-dimethylformamide (15 mL) and methyl hydrazine (7.6 g, 160 mmols, 3 equivalents). The mixture was stirred at room temperature for 1 hour and then heated at 75 degrees Celcius for 4 hours. The volatiles were removed by rotary evaporation and the crude residue was taken up in a small volume of methylene chloride. This red solution was applied to a cartridge of silica gel. The cartridge was eluted with a 20:80 mixture of ethyl acetate and hexanes, respectively. The appropriate fractions were combined and concentrated to produce 12.5 g of a white solid.

Provenance & Evidence