Water → 2-(3-Fluorophenyl)-6-(trifluoromethyl)pyrazolo[1,5-A]pyridine

Participants

Reaction Conditions

Reaction Steps

To a suspension of 1-(3-fluorophenyl)-2-[5-(trifluoromethyl)-2-pyridinyl]ethanone oxime (5.0 g, 16.77 mmol) in DME (20 ml) at −5° C. was added MsCl (1.3 ml, 16.77 mmol). The suspension was stirred at −5° C. for 10-15 min, and then Et3N (4.8 ml, 34.37 mmol) was added at a rate to maintain the temperature at or below 0° C. After the addition was complete, the suspension was warmed to room temperature. After 1 h an additional 0.5 eq. of Et3N was added to drive the reaction to completion. After an additional 0.5 h stirring, the suspension was filtered into a clean flask. DME (10 ml) was used to wash the salt cake. To the solution was added FeCl3 (27 mg, 0.167 mmol) in one portion. The resultant dark solution was heated to 70° C. and stirred for 1.5 h. The solution was then cooled to room temperature before the addition of H2O (50 ml) and ethyl acetate (100 ml). The layers were separated and the ethyl acetate layer was washed with 1 M HCl (50 ml) followed by brine (50 ml). The solution was filtered through a short plug of silica to remove any residual iron salts. The solution was concentrated under reduced pressure to afford 4.32 g (92%) of the title compound as a tan solid.

Provenance & Evidence