Triethylamine → ethyl 2-{[5-(benzyloxy)-N-(tert-butoxycarbonyl)-L-norvalyl]amino}-3-oxobutanoate

Participants

Reaction Steps

(S)-2-(tert-butoxycarbonylamino-5-benzyloxypentanoic acid dicyclohexylamine salt (10.0 g, 19.8 mmol) was purified by silica gel column chromatography (ethyl acetate to ethyl acetate:methanol=19:1) in order to remove dicyclohexylamine. The resulting oil, ethyl 2-amino-3-oxobutanoate (3.60 g, 19.8 mmol), ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (5.69 g, 29.7 mmol), 1-hydroxybenzotriazole (4.01 g, 29.7 mmol), triethylamine (6.87 mL, 49.5 mmol), in chloroform (40 mL) was stirred for 6 h at room temperature, and then reaction mixture was poured into water. The organic layer was separated, washed with saturated brine, dried over sodium sulfate, filtrated and concentrated in vacuo. The crude was purified by silica gel column chromatography (hexane:ethyl acetate=9:1 to 3:2) to give ethyl 2-{[5-(benzyloxy)-N-(tert-butoxycarbonyl)-L-norvalyl]amino}-3-oxobutanoate. MS (APCI): m/z 468 (M+NH4).

Provenance & Evidence