ethyl (2S)-2-amino-3-hydroxypropanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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%). Hobt (4 g, 29.6 mmol, 1.2 equiv.) was added Stirring The resulting mixture was stirred for 1.5 hrs 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 the solvent removed in a rotary evaporator The residue was dried in a vacuum oven (50° C.)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Analogously to Example 1, by using equivalent quantities, reacting N-acetyl-6-benzhydrylaminocaproic acid and ethyl L-serinate and suitable processing, dissolving the evaporation residue in ethanol, adding an ethanolic solution of potassium hydroxide, stirring for 12 hours at room temperature and further processing yields N-(N-acetyl-6-benzhydrylaminohexanoyl)-L-serine.