Triethylamine → [2-(2-Carbamoyl-pyrrolidin-1-yl)-2-oxo-ethyl]-carbamic acid tert-butyl ester

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Reaction Steps

N-tert-butyloxycarbonyl glycine 1a (5 g, 28.56 mmol) and L-prolinamide (3.25 g, 28.50 mmol) were dissolved in 75 mL of N,N-dimethylformamide, the resulting solution was cooled down to 0° C. (centigrade), and 1-hydroxybenzotriazole (11.8 g, 87.3 mmol), N-ethyl-N′-(dimethylaminopropyl)-carbodiimide (11.3 g, 59 mmol) and triethylamine (12.1 mL, 87.3 mmol) were then added with stirring. Upon completion of the addition, the reaction mixture was allowed to increase to room temperature, and stirred overnight. After thin lay chromatography showed the starting material disappeared, N,N-dimethylformamide was evaporated below 50° C., and the reaction solution was extracted with ethyl acetate (200 mL×3). The combined organic extracts were washed with 50 mL of saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by recrystallization with ethyl acetate to obtain the title compound [2-(2-carbamoyl-pyrrolidin-1-yl)-2-oxo-ethyl]-carbamic acid tert-butyl ester 1b (7.42 g, yield 95.8%) as a white powder.

Provenance & Evidence