Water → 3-Cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoroacetylpyrazole

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Reaction Steps

To a stirred solution of 3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-iodopyrazole (4.62 g) in tetrahydrofuran (100 ml) at -75° C. under an atmosphere of nitrogen was added, at such a rate that the temperature of the reaction mixture did not exceed -75° C., n-butyllithium (4.7 ml of a 2.5M solution in hexanes). A solution of methyl trifluoroacetate (1.93 ml) in tetrahydrofuran (5 ml) was then added at such a rate that the temperature of the reaction mixture did not exceed -75° C. Upon completion of the addition the mixture was allowed to warm to room temperature. Water (100 ml) was added and the mixture extracted twice with ethyl acetate (80 ml). The combined organic layers were dried (Na2SO4) and evaporated to give a brown gum which was purified by column chromatography on silica gel (250 g) eluted with dichloromethane. Combination and evaporation of suitable fractions gave the title compound as a pale yellow solid, m.p. 124-125° C.

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