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温度

0 °C

(tert-Butoxycarbonylamino)acetic acid (4.00 g, 22.8 mmol) was dissolved in dichloromethane (8 ml). Ethanol (1.60 ml, 27.40 mmol) and 4-dimethylaminopyridine (0.31 g, 25.1 mmol) were added. The solution was cooled to 0° C. N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (4.81 g, 25.11 mmol) was added. The solution was stirred for 16 h, while warming up to room temperature. It was diluted with ethyl acetate (150 ml) and 10% aqueous sodium hydrogen sulfate solution (100 ml). The phases were separated. The aqueous phase was extracted with ethyl acetate (4×50 ml). The combined organic layers were washed with saturated sodium hydrogen carbonate solution (150 ml) and dried over magnesium sulfate. The solvent was removed in vacuo. The crude product was purified by flash chromatography on silica (100 g), using ethyl acetate/heptane (1:4) as eluent, to give 4.25 g of ethyl 2-(tert-butoxycarbonylamino)acetate.

1. temperaturewhile warming up to room temperature
2. customThe phases were separated
3. extractionThe aqueous phase was extracted with ethyl acetate (4×50 ml)
4. washThe combined organic layers were washed with saturated sodium hydrogen carbonate solution (150 ml)
5. dry with materialdried over magnesium sulfate
6. customThe solvent was removed in vacuo
7. customThe crude product was purified by flash chromatography on silica (100 g)