Benzyl Thiocyanate → 5-Benzylthio-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulphonylpyrazole

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Reaction Steps

A solution of 5-bromo-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulphonylpyrazole (3.0 g) in dry tetrahydrofuran (32 ml), stirred under nitrogen at -78° C., was treated with a solution of n-butyllithium in hexane (2.8 ml of a 2.5M solution) over a period of 5 minutes. After 1 hour at -78° C., a solution of benzyl thiocyanate (0.95 g) in tetrahydrofuran (2 ml) was added. The stirred mixture was allowed to warm slowly to room temperature during 16 hours, then poured onto ice/water (50 ml) and extracted with ether (3×50 ml). The combined extracts were dried over anhydrous magnesium sulphate, evaporated in vacuo, and purified by chromatography, eluting with ethyl acetate/hexane (2:98). The product was triturated with hexane to give 5-benzylthio-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulphonylpyrazole (0.25 g), as a white solid, m.p. 117°-119° C.

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