[1-(2-Oxo-2-phenyl-ethylcarbamoyl)-ethyl]-carbamic acid benzyl ester

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available N-α-CBZ-L-alanine (2.11 g, 9.5 mmol) in dichloromethane (50 mL) was added 2-aminoacetophenone hydrochloride (1.62 g, 9.5 mmol). The resulting solution was cooled to 0° C. and N-methylmorpholine (1.15 g, 11 mmol), 1-hydroxybenzotriazole (2.55 g, 18.9 mmol) and 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (2.35 g, 12.3 mmol), in that order, were added under an Argon atmosphere. The reaction mixture was warmed to room temperature and stirred overnight. The reaction was quenched by addition of saturated aqueous NaHCO3 solution; the separated organic phase was washed with 2N citric acid, saturated NaHCO3 solution and brine, then dried over MgSO4 overnight. After filtration and concentration, the residue was purified by column chromatography on silica gel (eluent, EtOAc:hexane-1:1) to yield the title compound, [1-(2-oxo-2-phenyl-ethylcarbamoyl)-ethyl]-carbamic acid benzyl ester. The reaction mixture was warmed to room temperature The reaction was quenched by addition of saturated aqueous NaHCO3 solution the separated organic phase was washed with 2N citric acid, saturated NaHCO3 solution and brine dried over MgSO4 overnight After filtration and concentration the residue was purified by column chromatography on silica gel (eluent, EtOAc:hexane-1:1)