Reacción #90221

Ecuación de reacción

1,2-dibromotetrachloroethane

N-dimethylsulfamoylpyrazole

n-butyllithium

→

title product

Rendimiento 89.4%

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

Rendimiento 89.4%

Disolventes

tetrahydrofuran

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturawhile maintaining the temperature below −60° C
2. 2
   OtroA thick solid formed during the addition
3. 3
   workup.ADDITIONUpon completion of the addition the reaction mixture
4. 4
   Temperaturawas maintained for an additional 15 minutes
5. 5
   Temperaturawhile maintaining the temperature below −70° C
6. 6
   OtroThe −78° C. bath was removed
7. 7
   Otrothe reaction was quenched with water (600 mL)
8. 8
   ExtracciónThe reaction mixture was extracted with methylene chloride (4×)
9. 9
   Secadothe organic extracts were dried over magnesium sulfate
10. 10
    Concentraciónconcentrated
11. 11
    OtroThe crude product was further purified by chromatography on silica gel

Procedimiento

To a solution of N-dimethylsulfamoylpyrazole (44.0 g, 0.251 mol) in dry tetrahydrofuran (500 mL) at −78° C. was added dropwise a solution of n-butyllithium (2.5 M in hexane, 105.5 mL, 0.264 mol) while maintaining the temperature below −60° C. A thick solid formed during the addition. Upon completion of the addition the reaction mixture was maintained for an additional 15 minutes, after which time a solution of 1,2-dibromotetrachloroethane (90 g, 0.276 mol) in tetrahydrofuran (150 mL) was added dropwise while maintaining the temperature below −70° C. The reaction mixture turned a clear orange; stirring was continued for an additional 15 minutes. The −78° C. bath was removed and the reaction was quenched with water (600 mL). The reaction mixture was extracted with methylene chloride (4×), and the organic extracts were dried over magnesium sulfate and concentrated. The crude product was further purified by chromatography on silica gel using methylene chloride-hexane (50:50) as eluent to afford the title product as a clear colorless oil (57.04 g).

Fuente