Sodium Hydroxide → 1-tert-butyl-5-(5-methyl-isoxazol-3-yl)-1H-pyrazole-4-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 1-tert-butyl-5-(5-methyl-isoxazol-3-yl)-1H-pyrazole-4-carboxylic acid methyl ester (7.37 g, 26.59 mmol) in methanol (17.7 mL, 1.5M) cooled to 0° C. was treated dropwise with a 4N aqueous sodium hydroxide solution (13.3 mL, 53.15 mmol). The reaction was allowed to slowly warm to 25° C. The reaction was stirred at 25° C. over-night. At this time, the reaction was concentrated in vacuo to remove methanol. The residue was diluted with water (150 mL) and was then extracted with dichloromethane (3×150 mL). These organics were discarded. The aqueous layer was then acidified to pH=1 with a 2N aqueous hydrochloric acid solution. This solution was extracted with a 90/10 dichloromethane/methanol solution (3×150 mL). The combined organics were dried over sodium sulfate, filtered and concentrated in vacuo to afford 1-tert-butyl-5-(5-methyl-isoxazol-3-yl)-1H-pyrazole-4-carboxylic acid (5.42 g, 82%) as a brown solid. The material was used without further purification.

Provenance & Evidence