Cesium fluoride → 3-Cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-5-fluoro-4-trifluoromethanesulphonylpyrazole

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Reaction Conditions

Reaction Steps

A mixture of dry sulpholane (15 ml) and 4Å molecular sieve (3.0 g) was stirred under nitrogen with caesium fluoride (2.4 g) at 60° C. for 1,2 hour. To this was added 5-bromo-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethanesulphonylpyrazole (2.0 g) and the mixture stirred at 60° C. for 2 hours, and left overnight at room temperature. This was diluted with ether (50 ml), filtered, and washed with water (100ml). The aqueous layer was reextracted with ether (3×50 ml) and the combined organic solution re-washed with water (4×50ml), dried over anhydrous magnesium sulphate, and evaporated in vacuo to give an oil. Purification by chromatography, eluting with ether/hexane (1:4) gave 3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-5-fluoro-4-trifluoromethanesulphonylpyrazole (0.17 g), m.p. 95°-98° C., in the form of a white solid, after recrystallisation from hexane.

Provenance & Evidence