Reaction #792161

Reaction equation

hexachloroethane

N-dimethylsulfamoylpyrazole

n-butyllithium

→

title product

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

Solvents

tetrahydrofuran

hexane

tetrahydrofuran

Conditions

Workup

1. 1
   workup.ADDITIONUpon completion of the addition the reaction mixture
2. 2
   Temperaturewas maintained at ˜78° C. for an additional 45 minutes
3. 3
   TemperatureThe reaction mixture was maintained for an hour at ˜78° C.
4. 4
   Temperaturewarmed to ˜20° C.
5. 5
   Otherquenched with water (1 L)
6. 6
   ExtractionThe reaction mixture was extracted with methylene chloride (4×500 mL)
7. 7
   Dryingthe organic extracts were dried over magnesium sulfate
8. 8
   Concentrationconcentrated
9. 9
   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-butyllithium (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 the title product compound as a yellow oil (160 g).

Source