Reaction Steps
HF/pyridine (50 μL) was added dropwise to a stirred solution of 30 (20.0 mg, 0.0087 mmol) in THF (3 mL). The reaction mixture was stirred at room temperature for 5 h, after which it was diluted with ethyl acetate (15 mL), and washed with saturated aqueous NaHCO3 (2×25 mL) and brine (2×20 mL). The organic phase was dried (MgSO4) and filtered. Next, the filtrate was concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/ethyl acetate, 3/1-4/3, v/v) to give 32 as a white solid (16.0 mg, 84%). Rf=0.38 (hexane/ethyl acetate, 1/1, v/v). 1H NMR (500 MHz, CDCl3): δ 7.39-7.19 (m, 24H, aromatic), 6.36 (d, 1H, JNH′,2′=7.0 Hz, NH′), 6.28 (d, 1H, JNH,2=9.5 Hz, NH), 5.52 (d, 1H, J1′,2′=9.0 Hz, H-1′), 5.51 (t, 1H, =J3′,4′=9.5 Hz, H-3′), 5.41 (t, 1H, J2,3=J3,4=10.0 Hz, H-3), 5.27-5.25 (m, 1H, H-3L), 5.15-4.96 (m, 6H, H-1, H-3L, C6H4(CH2O)2P), 4.64-4.43 (m, 9H, H-4′, 4×CH2Ph), 4.23-4.19 (m, 1H, H-2), 4.13-4.09 (m, 1H, H-5), 3.94-3.82 (m, 4H, H-6a, H-6′a, 2×H-3S), 3.76-3.69 (m, 3H, H-5′, H-6′a, H-6b), 3.36-3.33 (m, 2H, H-2′, H-4), 2.69-2.27 (m, 12H, 2×H-2L, 2×H-2S, 2×H-2L′), 1.58 (broad, 12H, 2×H-4L, 2×H-4S, 2×H-3L′),1.26 (broad, 108H, 54×CH2, lipid), 0.91-0.81 (m, 18H, 6×CH3, lipid). HR MS (m/z) calculated for C130H207N2O22PSi[M+Na]+, 2202.4776; found, 2202.8279.
