Reaction Steps
N-(Tert-butoxycarbonyl-valinyl-alaninyl)-4-amino-5-benzyloxy-2-oxotetrahydrofuran (590.4 mg) was dissolved in 15 mL of trifluoroacetic acid, aged for 15 minutes, and concentrated. The residue was dissolved in methanol, diluted with toluene and concentrated to give a colorless solid. To 201.9 mg of this solid was added 3-phenylpropionic acid (123 mg, 0. 8216 mmol), hydroxybenzotriazole (111 mg, 0.8216 mmol), dimethyl formamide (3 mL), and 4-methylmorpholine (45 μl, 0.4108 mmol). Ethyl dimethylaminopropyl carbodiimide (83 mg, 0.4313 mmol) was added and the mixture stirred for 16 hours at ambient temperature. The mixture was diluted with ethyl acetate and washed three times with 2N hydrochloric acid, and twice with dilute sodium bicarbonate. The organics were dried over sodium sulfate, filtered and concentrated to give the title compound as a mixture of two diastereomers: 1H NMR (400 MHz, CD3OD) δ7.4-7.1 (m, 10H, Ar--H), 5.63 (d, 0.5H, J=5.03 Hz, CHOBn), 5.45 (d, 0.5H, J=1.20 Hz, CHOBn), 4.95-4.6 (m, 2.5H, CH2Ph, CHN), 4.4-4.2 (m, 1.5H, CHN), 4.08 (d, 0.5H, J=7.38 Hz, CHN), 4.03 (d, 0.5H, J=7.15 Hz, CH N), 3.03 (dd, 0.5H, J=8.11, 18.3 Hz, CHHCO2), 2.89 (dd, 2H, J=5.49, 8.79 Hz, CH2CON), 2.76 (dd, 0.5H, J=8.76, 17.38 Hz, CHHCO2), 2.7-2.4 (m, 3H, CHHCO2, CH2CH2Ph), 1.98 (m, 1H, CH(CH3)2), 1.31 (d, 1.5H, CHCH3), 1.25 (d, 1.5H, CHCH), 0.87 (m, 6H, CH(CH3)2. ##STR36## N-(3-Phenylpropionyl-valinyl-alaninyl)-3-amino-4-oxobutanoic acid
