Reaction Steps
A solution of 9-fluorenylmethyl N-succinimidyl carbonate (203 mg, 0.60 mmol) in DMF (3.0 mL) was added to a solution of 18a (219 mg, 0.37 mmol) in 9% Na2CO3 (803 mg, 0.68 mmol) at 0° C. and stirred overnight at room temperature. The pH was adjusted to 7.0 with 0.1 N HCl. The mixture was concentrated to an oil and purified by flash chromatography (CHCl3, then 95% CHCl3/MeOH) to give 11a (150 mg, 50%) as a colorless oil: 1H NMR δ 1.15-1.94 (m, 14H), 3.10-3.52 (m, 7H), 3.66-3.98 (m, 2H), 4.05-4.21 (m, 2H), 4.24-4.61 (m, 3H), 5.04 (s, 2H), 5.08 (s, 2H), 7.21-7.40 (m, 14H), 7.65 (dd, 2H, J=6.9, 4.2), 7.77 (d, 2H, J=7.2); 13C NMR δ 21.1, 21.7, 24.1, 26.4, 26.5, 28.2, 28.9, 32.1, 32.5, 32.6, 33.2, 34.3, 38.1, 38.5, 51.9, 52.4, 55.5, 64.1, 65.2, 67.4, 67.9, 68.3, 74.9, 79.5, 100.0, 101.5, 120.9, 126.3, 128.2, 128.80, 128.97, 129.10, 129.20, 129.48, 129.57, 129.62, 138.2, 138.5, 142.6, 145.2, 145.4, 158.1, 158.6, 176.8; HRMS m/z calcd for C46H54N3O10 808.3809, found 808.3833.
