1,2-Dibromo-1,1,2,2-tetrachloroethane → 3-Bromo-1-(dimethylsulfamoyl)pyrazole

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).

1. temperaturewhile maintaining the temperature below −60° C
2. customA thick solid formed during the addition
3. additionUpon completion of the addition the reaction mixture
4. temperaturewas maintained for an additional 15 minutes
5. temperaturewhile maintaining the temperature below −70° C
6. customThe −78° C. bath was removed
7. customthe reaction was quenched with water (600 mL)
8. extractionThe reaction mixture was extracted with methylene chloride (4×)
9. dry with materialthe organic extracts were dried over magnesium sulfate
10. concentrationconcentrated
11. customThe crude product was further purified by chromatography on silica gel

ORD-Eintrag

ord-6ad9405f46654916be0935a9c9d1d436

Quelldatensatz

uspto-grants-2016_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US09445593B1