Potassium bisulfate → tert-Butyl (S,S)-[4-(2-benzyloxycarbonylamino-propionyl)-3-methoxycarbonylmethyl-2-oxopiperazin-1-yl]acetate

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Reaction Steps

tert-Butyl (S)-(3-methoxycarbonylmethyl-2-oxo-piperazin-1-yl)acetate (3.0 g) and benzyloxycarbonyl-L-alanine (2.61 g) were dissolved in acetonitrile (40 ml). While stirring the solution at room temperature, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (2.45 g) was added to the solution, and the mixture was stirred for 3 hours at room temperature. The reaction mixture was poured into a 5% aqueous solution of potassium hydrogen sulfate and the solution was extracted with ethyl acetate, washed with a saturated aqueous solution of sodium hydrogen carbonate and dried over anhydrous magnesium sulfate (MgSO4). The solution was concentrated under reduced pressure. The residue was purified by means of a silica gel column chromatography (eluent:hexane:ethyl acetate=1:4) to give the titled compound (3.83 g) as a pale yellow amorphous powdery product.

Provenance & Evidence