Diisopropylethylamine → ethyl 1-(5-fluoropyridin-2-yl)-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

To (E)-ethyl 2-(ethoxymethylene)-4,4,4-trifluoro-3-oxobutanoate (0.441 g, 1.835 mmol) in ethanol (2 mL) was added diisopropylethylamine (0.427 mL, 2.447 mmol) followed by 5-fluoro-2-hydrazinylpyridine, hydrofluoride (0.3 g, 2.039 mmol) dissolved in 1 mL of ethanol (slightly exothermic). The reaction mixture was heated at 80° C. for 1 h. The reaction mixture was concentrated under reduced pressure, dissolved in dichloromethane (2 mL) and subjected to column chromatography using an ISCO setup (40 g, RediSep® silica gel column). The desired fractions were collected and concentrated to yield ethyl 1-(5-fluoropyridin-2-yl)-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate (0.165 g, 27%) as a white solid. LC/MS M+1=304.

Provenance & Evidence