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温度

0 °C

Benzo[1,2,3]thiadiazole-5-carboxylic acid (2.70 g, 15.0 mmol) was dissolved in tetrahydrofuran (25 mL) and cooled to 0° C. To this was added triethylamine (2.50 mL, 18.0 mmol) followed by isobutylchloroformate (2.15 mL, 16.5 mmol) in a dropwise manner. The resulting slurry was stirred for a further 30 minutes at 0° C. and then filtered into a mixture of sodium borohydride (1.14 g, 30 mmol) in ice water (20 mL). The resulting mixture was stirred at 0° C. for 15 minutes, evaporated to one quarter of its volume and then partitioned between a saturated aqueous solution of sodium hydrogen carbonate (20 mL) and ethyl acetate (3×50 mL). The organic phases were combined and then dried over sodium sulfate. This was followed by concentration under reduced pressure to provide an oil which was purified by column chromatography on silica gel using an ethyl acetate and hexane solvent system. This provided the desired product as a yellow solid (1.40 g, 56%).

1. stirringThe resulting mixture was stirred at 0° C. for 15 minutes
2. customevaporated to one quarter of its volume
3. custompartitioned between a saturated aqueous solution of sodium hydrogen carbonate (20 mL) and ethyl acetate (3×50 mL)
4. dry with materialdried over sodium sulfate
5. concentrationThis was followed by concentration under reduced pressure
6. customto provide an oil which
7. customwas purified by column chromatography on silica gel using an ethyl acetate and hexane solvent system