Sodium borohydride → 5-(3-Butyl-5-hydroxymethyl-isoxazol-4-ylmethoxy)-2-methyl-2H-pyrazole-3-carboxylic acid methyl ester

Participants

Reaction Steps

To a solution of 5-(3-butyl-5-formyl-isoxazol-4-ylmethoxy)-2-methyl-2H-pyrazole-3-carboxylic acid methyl ester (80 mg, 0.25 mmol) in methanol (4 mL) was added sodium borohydride (18.8 mg, 0.5 mmol) in portions over 3 min. Upon addition, the reaction became a clear light yellow solution containing a black precipitate. After stirring at room temperature for 1.5 h, the mixture was filtered over Celite® and the filter cake was washed with methanol. The filtrate was concentrated and the residue was portioned between 0.5M aqueous hydrochloric acid and ethyl acetate. The aqueous phase was extracted two times with ethyl acetate and the combined organic phases were washed with brine, dried over sodium sulfate and concentrated to a yellow oil. The crude material was purified by chromatography (silica, heptane:acetone 7.5:2.5) to afford the title compound (37 mg, 46%) as a dark brown oil. MS: m/e=324.3 [M+H]+.

Provenance & Evidence