1-Ethyl-3-(3'-dimethylaminopropyl)carbodiimide → 2-Benzyloxycarbonylamino-4-(1-ethoxycarbonyl-2-hydroxy-ethylcarbamoyl)-butyric acid ethyl ester

Beteiligte Stoffe

Reaktionsschritte

A suspension of acid (3) (7.6 g, 24.57 mmol) in dry acetonitrile (80 ml) was stirred under nitrogen at room temperature and Hobt (4 g, 29.6 mmol, 1.2 equiv.) was added. Stirring was continued for 10 min., and EDCI (5.1 g, 26.6 mmol, 1.1 equiv.) was added. The resulting mixture was stirred for 1.5 hrs and serine ethyl ester free base (3.27 g, 24.57 mmol, 1 equiv.) in acetonitrile (20 ml) was added. Stirring was continued at room temperature for 3 hrs. The solvent was removed in a rotary evaporator, the residue was partitioned between water (100 ml) and ethyl acetate (200 ml) and phases were separated. The organic phase was washed successively with water (50 ml), 5% potassium carbonate (2×50 ml) and water (2×50 ml), dried over sodium sulfate and the solvent removed in a rotary evaporator. The residue was dried in a vacuum oven (50° C.) to produce (4) (12.4 g, 85.5%).

Herkunft & Nachweise