Diisopropylethylamine → tert-Butyl [(S)-2-allyloxycarbamoyl-2-(4-isobutyrylpiperazin-1-yl)ethyl]carbamate

Participants

Reaction Steps

1.4 g (4.4 mmol) of O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumtetrafluoroborate and then 2.3 ml (13.1 mmol) of diisopropylethylamine are added to a solution of 1.5 g (4.4 mmol) of (S)-3-tert-butoxycarbonylamino-2-(4-isobutyrylpiperazin-1-yl)propanoic acid in 20 ml of dimethylformamide. After stirring at ambient temperature for 15 min, a solution of 500 mg (4.6 mmol) of O-allylhydroxylamine hydrochloride and of 0.8 ml (4.6 mmol) of diisopropylethylamine in 10 ml of dimethylformamide is added. The reaction medium is stirred at ambient temperature for 20 h, hydrolyzed with a saturated aqueous solution of sodium hydrogen carbonate, and then diluted with ethyl acetate. The organic phase is washed with a saturated aqueous solution of sodium chloride, dried over magnesium sulfate, filtered and concentrated under vacuum, 1.45 g (83%) of tert-butyl [(S)-2-allyloxycarbamoyl-2-(4-isobutyrylpiperazin-1-yl)ethyl]carbamate are obtained in the form of a colorless oil.

Provenance & Evidence