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(S)-2-((S)-2-Benzyloxycarbonylamino-propionylamino)-5-{3-[(S)-3-((S)-2-benzyloxycarbonylamino-propionylamino)-3-carboxy-propyl]-ureido}-5-oxo-pentanoic acid[ No CAS ]
1. Preparation of Z-Ala-Gln-OH To a solution of 4.80 g of <strong>[3401-36-3]Z-Ala-OSu</strong> in 60 ml of tetrahydrofuran was added a solution of 2.19 g of H-Gln-OH in 40 ml of water and 2.10 ml of triethylamine and the mixture was stirred at a room temperature for 20 hours. Tetrahydrofuran and water were removed by distillation and the residue thus obtained was extracted with n-butanol. The n-butanol extract was washed with a 2%-acetic acid and butanol was removed by distillation. The precipitated substance thus obtained was collected by filtration and reprecipitated with methanol-ethyl acetate to obtain 3.87 g of Z-Ala-Gln-OH.
2(a). Preparation of H-Ala-Gln-OH 3.50 Grams of Z-Ala-Gln-OH was dissolved in 50 ml of water and 30 ml of methanol, and the mixture was catalytically reduced by using palladium as a catalyst to obtain H-Ala-Gln-OH.