Triethylamine → Nepsilon-Benzyloxycarbonyl-Nalpha-(tert-butoxycarbonyl)-L-lysylglycine ethyl ester

Participants

Reaction Steps

To a solution of 0.73 g (5.26 mmol) of glycine ethyl ester hydrochloride and 0.74 mL (5.26 mmol) of triethylamine in 42 mL of chloroform were added successively, at 0° C., 2.0 g (5.26 mmol) of Nε -benzyloxycarbonyl-Nα -(tert-butoxycarbonyl)-L-lysine and 1.09 g (5.26 mmol) of dicyclohexylcarbodiimide. The reaction mixture was stirred overnight at room temperature. The resulting precipitate was removed by filtration and the filtrate was washed successively with 0.5N hydrochloric acid, water, 3% aqueous sodium bicarbonate solution and water, then dried over anhydrous sodium sulfate. Evaporation of the solvent afforded a residue which was triturated with ethyl acetate. Insoluble materials were removed by filtration and the filtrate was evaporated in vacuo. The residue was recrystallized from a mixture of ethyl acetate and isopropyl ether to give 1.15 g (48%) of the title compound as colorless crystals. The mother liquor was concentrated under reduced pressure and the residue was crystallized as before to give a second crop of crystals (0.77 g, 32.1%). Total yield 80.1%, melting point 69°-70° C. NMR and IR spectral analyses confirmed the identity of the product, which has the formula: ##STR85##

Provenance & Evidence