Reaction Steps
(S)-5-(4-Benzyloxy-phenyl)-4-(7-phenyl-heptanoylamino)-pentanoic acid methyl ester (0.86 g, 1.7 mmol) and NaOH solution (4 M, 0.85 mL, 3.4 mmol) in MeOH-THF (1:1, 6 mL) was stirred at room temperature overnight. The solvent was removed, and the residue diluted with water. The solution was washed with Et2O, acidified with 5% aqueous HCl, and extracted with EtOAc. The organic phase was then washed with brine, dried Na2SO4) and the solvent removed under reduced pressure to afford (63), 0.81 g (98%), m.p. 127.7-129.5° C. 1H NMR (DMSO-d6) δ 1.13-1.23 (6H, m, 3×CH2), 1.35-1.44 (2H, m, CH2), 1.47-1.54 (2H, m, CH2), 1.95-2.00 (2H, m, CH2), 2.14-2.22 (2H, m, CH2), 3.86 (1H, br s, H58□ 5.02 (2H, s, OCH2Ph), 6.89 (2H, d, J=8.6 Hz), 7.08 (2H, d, J=8.5 Hz), 7.15-7.44 (10H, m, 10×Ar—H), 7.50 (1H, br d, J=8.6 Hz, NH), 12.01 (1H, br s, CO2H). 13C NMR (DMSO-d6) δ 25.3, 28.4, 28.5, 29.3, 30.5, 31.0, 35.2, 35.5, 49.3, 114.3, 125.6, 127.7, 127.8, 128.2, 128.4, 130.1, 131.1, 137.2, 142.3, 156.7, 171.7, 174.3.
