Carbon Dioxide → Tert-butyl (5-chloro-2,4-difluorophenyl)sulfonyl(thiazol-4-yl)carbamate

참여 물질

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To a solution of thiazol-4-yl-carbamic acid tert-butyl ester (Preparation 72, 503 mg, 0.00251 mol) in tetrahydrofuran (5.0 mL) cooled to −78° C. was added lithium hexamethyldisilazide (1.0 M in tetrahydrofuran, 2.76 mL, 0.00276 mol). The reaction was stirred for 30 minutes at room temperature and then cooled to −78° C. A solution of 5-chloro-2,4-difluorobenzenesulfonyl chloride (620.5 mg, 0.002512 mol) in tetrahydrofuran (5.0 mL) was added slowly via syringe. After addition was complete, the reaction mixture remained immersed in the cooling bath; the temperature of the dry ice bath was not maintained, allowing the reaction mixture to slowly warm to room temperature. After 24 hours, the reaction mixture was poured into saturated aqueous ammonium chloride solution and extracted with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered and concentrated in vacuo onto Celite™. The residue was purified by automated flash chromatography (40 g SiO2) eluting with ethyl acetate:dichloromethane (gradient 0:1 to 5:95, by volume) to afford the title compound as a white solid, 733 mg, 71% yield.

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