Reaction Steps
To a solution of (S)-methyl 2-(benzyloxycarbonylamino)-3-((2S,3S,4S)-4-hydroxy-2,3-bis(2-methylallyloxy)pentyloxy)propanoate (480 mg, 1.001 mmol) in THF/H2O (18 mL, 2:1 ratio) was added LiOH (71.9 mg, 3.00 mmol) and the solution was allowed to stir for 40 minutes (min) at ambient temperature. The crude reaction mixture was diluted with EtOAc and washed with 1 Normal (N) aqueous HCl. The phases were separated and the aqueous phase was extracted with EtOAc (3×20 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated to furnish the intermediate acid as a colorless oil which was dissolved in anhydrous toluene (50 mL) and added to a solution of MNBA (521 mg, 1.512 mmol) and DMAP (693 mg, 5.67 mmol) in toluene (180 mL) over the course of 3 h via syringe pump. After the addition was completed the reaction mixture was stirred for 1 h, concentrated, and purified by flash chromatography (SiO2) to afford the title compound as a white foam (281 mg, 62%): 1H NMR (400 MHz, CDCl3) δ 7.40-7.28 (m, 5H), 5.55 (d, J=7.7 Hz, 1H), 5.10 (s, 2H), 5.01-4.91 (m, 3H), 4.85 (d, J=1.2 Hz, 2H), 4.69 (dd, J=12.1, 6.7 Hz, 1H), 4.32 (d, J=11.7 Hz, 1H), 3.99-3.89 (m, 4H), 3.85 (d, J=11.3 Hz, 1H), 3.74 (dd, J=11.9, 4.5 Hz, 1H), 3.60-3.51 (m, 1H), 3.33-3.23 (m, 2H), 1.72 (d, J=6.2 Hz, 6H), 1.44 (d, J=6.3 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 170.85, 155.71, 142.26, 142.02, 136.10, 128.57, 128.25, 128.11, 112.33, 112.02, 84.95, 83.01, 77.63, 75.87, 74.89, 74.66, 72.86, 67.14, 54.26, 19.81, 19.66, 18.63; ESIMS m/z 470.3 ([M+Na]+).
