4-Methylmorpholine → N-(N-benzyloxycarbonyl-2-amino-4-Pentenoyl)-L-valine benzyl ester

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Reaction Steps

N-(N-Benzyloxycarbonyl-2-Amino-4-Pentenoyl)-L-Valine Benzxyl Ester (4) To a cooled (0-5° C.) solution of 24 mg (0.096 mmol) N-(N-benzyloxycarbonyl-2-amino-4-pentenoic acid (3), 36 mg (0.096 mmol) valine benzyl ester p-toluenesulfonyl salt, and 11 μL (0.096 mmol) N-methylmorpholine in 2 mL CH2Cl2 was added 14 mg (0.101 mmol) HOBt and 21 mg (0.101 mmol) DCC and the mixture was stirred for 19 h. The solution was filtered and the filtrate diluted with 10 mL CH2Cl2 and washed with two 10-mL portions of 0.5 N HCl, with two 10-mL portions of saturated aqueous NaHCO3, and with 10 mL brine. The organic phase was dried (MgSO4) and concentrated. The crude product was applied to a silica gel column (1×15 cm) and elution with 5% MeOH in CH2Cl2 gave pure N-(N-benzyloxycarbonyl-2-amino-4-Pentenoyl)-L-valine benzyl ester (4) as a colorless oil: yield 35 mg (83%); 1H NMR (CDCl3) δ0.80-0.90 (m, 6H); 2.14-2.20 (m, 1H); 2.49-2.56 (m, 2H); 4.20-4.32 (M, 1H); 4.55-4.60 (m, 1H0; 5.07-5.30 (M, 6H); 5.65-5.83 (m, 1H); 6.42-6.49 (m, 1H); 7.30-7.34 (m, 10H); mass spectrum (CI, methane) m/z 439 (M+H)+, 225.

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