Methylhydrazine → 3-cyclopropyl-1-methyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Steps

A mixture of methyl 3-cyclopropyl-3-oxopropanoate (10.0 g, 70.4 mmol) and 1,1-dimethoxy-N,N-dimethylmethanamine (10.1 g, 84.4 mmol) was stirred for 1 hr. The reaction mixture was concentrated under reduced pressure, and the residue was dissolved in diethyl ether (25 mL). A solution of methylhydrazine (3.56 g, 77.4 mmol) in diethyl ether (25 mL) was added dropwise with stirring under ice-cooling, and the mixture was stirred for 1 hr. The reaction mixture was diluted with ethyl acetate, washed with water and saturated brine, dried over anhydrous magnesium sulfate and filtrated. The filtrate was concentrated under reduced pressure, ethanol (35 mL) and 8N aqueous sodium hydroxide solution (17.5 mL) were added to the residue, and the mixture was stirred at room temperature for 15 hr. The reaction mixture was neutralized with 1N hydrochloric acid, and the precipitated solid was collected by filtration and washed with water to give a mixture (8.71 g, 75%) of 3-cyclopropyl-1-methyl-1H-pyrazole-4-carboxylic acid (1) and 5-cyclopropyl-1-methyl-1H-pyrazole-4-carboxylic acid (2) as a white solid.

Provenance & Evidence