Hexachloroethane → 5-chloro-N,N-dimethyl-3-(trifluoromethyl)-1H-pyrazole-1-sulfonamide

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Reaction Steps

Under a nitrogen atmosphere, N,N-dimethyl-3-(trifluoromethyl)-1H-pyrazole-1-sulfonamide (4.0 g, 16 mmol) (i.e. the product of Example 13, Step A) in tetrahydrofuran (25 mL) was cooled to −78° C. was then treated with n-butyllithium (2 M solution in cyclohexane, 8.6 mL, 17.2 mmol) dropwise. The reaction mixture formed a thick precipitate, and stirring was continued for 30 minutes after the addition. To the stirred suspension, a solution of hexachloroethane (4.2 g, 18 mmol) in tetrahydrofuran (15 mL) was added dropwise. After 1 h the resulting clear solution was warmed to ambient temperature and quenched with the addition of water (50 mL). The reaction mixture was extracted with dichloromethane and dried over MgSO4. The reaction mixture was filtered and concentrated under reduced pressure to give 4.38 g of the title compound. This compound was of sufficient purity to use in subsequent reactions.

Provenance & Evidence