Reaction Steps
To a solution of (2S,6S,7S)-benzyl 2-((tert-butoxycarbonyl)amino)-7-((S)-1-((4-methoxybenzyl)oxy)-ethyl)-10-methyl-6-propoxyundecanoate (1.10 g, 1.75 mmol) in H2O (0.531 mL) and DCM (5.31 mL) was added DDQ (0.418 g, 1.84 mmol) at 0° C. The mixture was stirred vigorously at this temperature for 1 h and then 1N NaOH (1.84 mL, 1.84 mmol) and H2O (20 mL) were added. The phases were separated and the aqueous phase was extracted with DCM (3×15 mL). The combined organic extracts were washed with brine (8 mL), dried over Na2SO4, filtered, and the filtrate was treated with Celite® (2 scoopula tip-fulls). The solvent was removed under reduced pressure and the resulting adsorbed material was directly loaded onto a column and purified using flash column chromatography (40 g SiO2, 0→60% EtOAc/hexanes) to afford the title compound (815 mg, 1.61 mmol, 92%) as a colorless oil: 1H NMR (400 MHz, CDCl3) δ 7.41-7.30 (m, 5H), 5.17 (app q, J=12.4 Hz, 2H), 5.07 (d, J=8.5 Hz, 1H), 4.44-4.39 (m, 1H), 4.39-4.30 (m, 1H), 3.87-3.75 (m, 1H), 3.54 (app dt, J=9.0, 6.6 Hz, 1H), 3.42-3.33 (m, 1H), 3.26 (app dt, J=8.9, 6.6 Hz, 1H), 1.87-1.76 (m, 1H), 1.72-1.37 (m, 17H), 1.35-1.07 (m, 7H), 1.04-0.93 (m, 1H), 0.93-0.84 (m, 9H); 13C NMR (101 MHz, CDCl3) δ 172.66, 155.32, 135.39, 128.59, 128.42, 128.24, 82.50, 79.89, 71.42, 69.10, 66.99, 53.52, 45.46, 37.47, 32.82, 28.82, 28.31, 28.28, 25.27, 23.20, 22.68, 22.54, 22.44, 22.06, 10.66; ESIMS m/z 530 ([M+Na]+).
