[C:1]([O:5][C:6]([NH:8][C@@:9]([CH3:20])([C:17]([OH:19])=O)[CH2:10][C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].Cl.CN(C)CCCN=C=NCC.O.ON1C2C=CC=CC=2N=N1.Cl.[NH2:45][CH2:46][C:47]([O:49][CH2:50][CH3:51])=[O:48].C(N(CC)CC)C>C(Cl)Cl>[C:1]([O:5][C:6]([NH:8][C@@:9]([CH3:20])([C:17]([NH:45][CH2:46][C:47]([O:49][CH2:50][CH3:51])=[O:48])=[O:19])[CH2:10][C:11]1[CH:12]=[CH:13][CH:14]=[CH:15][CH:16]=1)=[O:7])([CH3:2])([CH3:3])[CH3:4]To a stirring solution of (R)-N-(tert-butyloxycarbonyl)-α-methylphenylalanine (0.72 g, 2.6 mmol) in dry CH2Cl2 (16 mL) was added N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (0.69 g, 4.4 mmol) and 1-hydroxybenzotriazole hydrate (0.39 g, 2.9 mmol). The reaction was stirred at ambient temperature for 30 min and then glycine, ethyl ester hydrochloride (0.62 g, 5.2 mmol) and triethylamine (0.85 ml, 5.7 mmol) were added. After stirring at ambient temperature for 3 h, the reaction was transferred to a separatory funnel with CH2Cl2. Extraction with CH2Cl2 and washing of the organic layer with water, saturated NaHCO3, and brine and drying with MgSO4 afforded 0.94 g of crude product after evaporation of the solvent. Purification by flash chromatography (SiO2, 0.2 to 10% MeOH in CH2Cl2) afforded pure product (0.87 g, 93% yield). MS (ESI) 365 (M+H).
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