Reaction Steps
To a mixture of (2S,6R,7R,8S)-methyl 2-((tert-butoxycarbonyl)amino)-7-isobutoxy-8-((4-methoxybenzyl)oxy)-6-(2-(methylthio)ethyl)nonanoate (536 mg, 0.941 mmol) and 0.85 mL H2O in CH2Cl2 (9.4 mL) at 0° C. (icewater bath) was added DDQ (214 mg, 0.941 mmol). The resulting dark mixture was stirred at 0° C. for 3 h, then another portion of DDQ (41 mg, 0.180 mmol) were added and the reaction was stirred for 1 h. The reaction was quenched with sodium hydroxide (NaOH; 1.3 ml of 1M aqueous, 1.3 mmol) and stirred for 10 min. The reaction was then diluted with H2O (20 mL) and extracted with CH2Cl2 (3×20 mL). The combined organic extracts were dried over Na2SO4, filtered, and concentrated to provide a red oil which was purified by column chromatography on SiO2 (5→35% acetone/hexanes gradient) to furnish the title product as a clear, colorless oil (353 mg, 83%): 1H NMR (400 MHz, CDCl3) δ 5.02 (d, J=8.0 Hz, 1H), 4.31 (d, J=5.2 Hz, 1H), 3.95-3.83 (m, 1H), 3.74 (d, J=1.6 Hz, 3H), 3.36 (dd, J=8.5, 6.3 Hz, 1H), 3.22 (dd, J=8.5, 6.6 Hz, 1H), 3.05 (dd, J=5.6, 3.9 Hz, 1H), 2.58 (ddd, J=14.0, 8.7, 5.3 Hz, 1H), 2.47 (ddd, J=12.8, 8.3, 7.4 Hz, 1H), 2.10 (s, 3H), 1.96-1.68 (m, 4H), 1.68-1.49 (m, 3H), 1.45 (s, 9H), 1.39 (s, 4H), 1.21 (d, J=6.3 Hz, 3H), 0.91 (dd, J=6.7, 1.9 Hz, 6H); 13C NMR (101 MHz, CDCl3) δ 173.36, 155.36, 84.83, 79.93, 79.24, 68.10, 53.20, 52.27, 38.01, 33.20, 33.05, 32.76, 30.90, 29.21, 28.83, 28.33, 22.83, 19.52, 19.46, 19.11, 15.43; ESIMS m/z 450.4 ([M+H]+), 472.4 ([M+Na]+).
