Reaction #531819

Reaction equation

hexachloroethane

N-dimethylsulfamoylpyrazole

n-butyl-lithium

→

title product

Yield 71.3%

3-chloro-N,N-dimethyl-1H-pyrazole-1-sulfonamide

Yield 71.3%

Solvents

tetrahydrofuran

hexane

tetrahydrofuran

Conditions

Workup

1. 1
   workup.ADDITIONUpon completion of the addition the reaction mixture
2. 2
   TemperatureThe reaction mixture was maintained for an hour at −78° C.
3. 3
   Temperaturewarmed to −20° C.
4. 4
   Otherquenched with water (1 L)
5. 5
   ExtractionThe reaction mixture was extracted with methylene chloride (4×500 mL)
6. 6
   Dryingthe organic extracts were dried over magnesium sulfate
7. 7
   Concentrationconcentrated
8. 8
   OtherThe crude product was further purified by chromatography on silica gel

Procedure

To a solution of N-dimethylsulfamoylpyrazole (188.0 g, 1.07 mol) in dry tetrahydrofuran (1500 mL) at −78° C. was added dropwise a solution of 2.5 M n-butyl-lithium (472, mL, 1.18 mol) in hexane while maintaining the temperature below −65° C. Upon completion of the addition the reaction mixture was maintained at −78° C. for an additional 45 minutes, after which time a solution of hexachloroethane (279 g, 1.18 mol) in tetrahydrofuran (120 mL) was added dropwise. The reaction mixture was maintained for an hour at −78° C., warmed to −20° C. and then quenched with water (1 L). The reaction mixture was extracted with methylene chloride (4×500 mL); the organic extracts were dried over magnesium sulfate and concentrated. The crude product was further purified by chromatography on silica gel using methylene chloride as eluent to afford 160 g of the title product compound as a yellow oil.

Source