Pyrazole → N,N-dimethyl-1H-pyrazole-1-sulfonamide

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Reaction Steps

Pyrazole (12 g) was dissolved in tetrahydrofuran (200 mL), sodium hydride (60% in oil, 8.46 g) was added at 0° C. with stirring under a nitrogen atmosphere. After 20 min, dimethylsulfamoyl chloride (17 mL) was added dropwise, and the mixture was further stirred at the same temperature for 1 hr, and at room temperature for 1 hr. The reaction mixture was poured into saturated aqueous sodium hydrogen carbonate (400 mL), the mixture was extracted with ethyl acetate (400 mL), and the extract was dried over anhydrous magnesium sulfate. Insoluble material was filtered off, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane), and the object fraction was concentrated under reduced pressure to give the title compound (25.3 g) as a colorless oil.

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