反应详情

(R)-3-(tert-Butoxycarbonylamino)-2-methylpropanoic acid (465 mg, 2.3 mmol) was dissolved in dichloromethane (11 ml). 4-Dimethylaminopyridine (280 mg, 2.3 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (877 mg, 4.58 mmol) were added, followed by N-hydroxysuccinimide (290 mg, 2.52 mmol). After 4 h of stirring at room temperature, concentrated ammonium hydroxide (1.6 ml) was added slowly. The reaction mixture was stirred for an additional 20 min then aqueous HCl and ethyl acetate were added and the aqueous layer was extracted six times with ethyl acetate. The combined organic layers were washed with sodium bicarbonate solution and dried over sodium sulfate. After evaporation, the residue was purified by silica gel chromatography to give 335 mg (72%) of ((R)-2-carbamoyl-propyl)-carbamic acid tert-butyl ester. (M+Na)+=225.

1. stirringThe reaction mixture was stirred for an additional 20 min
2. extractionthe aqueous layer was extracted six times with ethyl acetate
3. washThe combined organic layers were washed with sodium bicarbonate solution
4. dry with materialdried over sodium sulfate
5. customAfter evaporation
6. customthe residue was purified by silica gel chromatography