tert-Butylhydrazine monohydrochloride → 1-tert-butyl-5-(5-methyl-isoxazol-3-yl)-1H-pyrazole-4-carboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 3-dimethylamino-2-(5-methyl-isoxazole-3-carbonyl)-acrylic acid ethyl ester (27.53 mmol) in absolute ethanol (41.7 mL) was treated with tert-butylhydrazine hydrochloride (3.57 g, 28.63 mmol) and sodium acetate (2.80 g, 34.13 mmol). The resulting mixture was heated to 90° C. for 18 h. At this time, the reaction was cooled to 25° C. The reaction was diluted with water (200 mL) and was then extracted with dichloromethane (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 methyl ester (7.37 g, 96%) as a black solid. The material was used without further purification.

Provenance & Evidence