(2,5-dioxopyrrolidin-1-yl) (2S)-2-[(2-methylpropan-2-yl)oxycarbonylamino]-6-(phenylmethoxycarbonylamino)hexanoate

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

Procedure: H-Glu(OBzl)OBzl (2.0 g) was dissolved in a mixture of acetonitrile (50 ml) and water (10 ml). The solution was cooled to 0° C. and triethylamine (400 mg) and Boc-Lys(Z)OSu (1.91 g) were added. The mixture was stirred at 0°-5° C. for 2 hours and at room temperature for 3 hours. The solvent was distilled off and the residue was poured into a mixture of ethyl acetate (100 ml) and 2.5% hydrochloric acid. The organic layer was washed with water (50 ml×2), 2.5% sodium hydrogen carbonate (50 ml) and water (50 ml×3) in that order and dried over magnesium sulfate. The solvent was then distilled off to give Boc-Lys(Z)-Glu(OBzl)OBzl (2.70 g). The solvent was distilled off the residue was poured into a mixture of ethyl acetate (100 ml) and 2.5% hydrochloric acid The organic layer was washed with water (50 ml×2), 2.5% sodium hydrogen carbonate (50 ml) and water (50 ml×3) in that order dried over magnesium sulfate The solvent was then distilled off

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

Procedure: A solution of 583 mg of H-Gly-Asp(OBzl)-Val-OBzl (Example 15Bb) and 477.5 mg of Boc-Lys(Z)-O Su in 10 ml of DMF is adjusted to pH 8.5 with N-methylmorpholine. After stirring for 18 hours the mixture is concentrated and the residue is partitioned between ethyl acetate and water. The organic phase is washed with saturated NaHCO3 solution, 5% KHSO4 /10% K2SO4 solution and saturated NaCl solution, dried and filtered. The filtrate is concentrated and the residue is crystallized from ether. There are obtained 385 mg of Boc-Lys(Z)-Gly-Asp(OBzl)-Val-OBzl, m.p. 95°-101° C. is concentrated the residue is partitioned between ethyl acetate and water The organic phase is washed with saturated NaHCO3 solution, 5% KHSO4 /10% K2SO4 solution and saturated NaCl solution dried filtered The filtrate is concentrated the residue is crystallized from ether

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

Procedure: H-Glu(OBzl)OBzl (2.0 g) was dissolved in a mixture of acetonitrile (50 ml) and water (10 ml). The solution was cooled to 0° C. and triethylamine (400 mg) and Boc-Lys(Z)OSu (1.91 g) were added. The mixture was stirred at 0°-5° C. for 2 hours and at room temperature for 3 hours. The solvent was distilled off and the residue was poured into a mixture of ethyl acetate (100 ml) and 2.5% hydrochloric acid. The organic layer was washed with water (50 ml×2), 2.5% sodium hydrogen carbonate (50 ml) and water (50 ml×3) in that order and dried over magnesium sulfate. The solvent was then distilled off to give Boc-Lys(Z)-Glu(OBzl)OBzl (2.70 g). The solvent was distilled off the residue was poured into a mixture of ethyl acetate (100 ml) and 2.5% hydrochloric acid The organic layer was washed with water (50 ml×2), 2.5% sodium hydrogen carbonate (50 ml) and water (50 ml×3) in that order dried over magnesium sulfate The solvent was then distilled off