Reaction Steps
A solution of 15 (497 mg, 0.64 mmol) in DMF (10 mL) was treated with sodium hydride (18.5 mg, 0.77 mmol) at 0° C. under an Ar atmosphere. After stirring at 0° C. for 30 min, benzyl 2-bromoacetate (0.15 mL, 0.96 mmol) was added. The mixture was stirred at 0° C. for another 30 min and then warmed to room temperature overnight. The solvent was evaporated to dryness and extracted with EtOAc/H2O. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated in vacuo. The crude product was purified by flash column chromatography, eluting with 40% EtOAc in Hexane (with 0.1% Et3N) to yield 453 mg (76%) of 16 as a light yellow oil. Rf=0.28 (in 40% EtOAc/hexane); 1H NMR (300 MHz, CDCl3) δ 7.32 (m, 5H), 6.96 (d, 2H, J=7.2 Hz), 6.86 (d, 1H, J=8.4 Hz), 6.72 (dd, 1H, J=7.8 and 1.5 Hz), 6.59 (m, 3H), 5.28 (s, 4H), 5.15 (s, 2H), 4.89 (s, 1H), 4.64 (s, 2H), 4.01 (s, 4H), 3.86 (m, 4H), 3.58 (m, 4H), 3.39 (s, 6H), 1.39 (s, 18H); 13C NMR (75 MHz, CDCl3) 6170.3, 168.8, 150.7, 149.9, 147.5, 146.6, 146.5, 144.4, 144.3, 139.1, 138.9, 135.3, 128.6, 128.4, 128.3, 122.9, 120.0, 117.0, 116.9, 116.2, 116.1, 115.8, 105.9, 94.7, 81.2, 71.5, 68.1, 66.7, 66.6, 59.0, 54.5, 42.6, 28.0; 19F NMR (282 MHz, CDCl3) δ −140.2 (dd, 2 F); mass spectrum, calculated for C46H55F2NO13 (M−17) 909.4, Found 910.1.
