Reaction Steps
A solution of compound 7 (10.9 g, 12 mmol) and pyridine (2 ml, 25 mmol) in CH2Cl2 (125 ml) at 0° C. was treated dropwise over 15 min with a solution of 2,2,2-trichloro-1,1-dimethylethyl chloroformate (3.17 g, 13.2 mmol) in CH2Cl2 (25 ml). The reaction mixture was allowed to warm slowly to ambient temperature over 3.5 h. 4-Pyrrolidinopyridine (0.89 g, 6.0 mmol), N,N-diisopropylethylamine (10.5 ml, 60 mmol) and diphenyl chlorophosphate (3.7 ml, 18 mmol) were added sequentially and the resulting mixture was stirred for 5 h at room temperature. The reaction mixture was diluted with CH2Cl2 (500 ml), washed with cold 7.5% aqueous HCl (2×250 ml), water (250 ml), saturated aqueous NaHCO3 (250 ml), dried (Na2SO4), and then concentrated. The residue obtained was purified by flash chromatography on silica gel eluting with 12.5% EtOAc-hexanes to give 15.1 g (95%) of 2-(trimethylsilyl)ethyl 2-deoxy-4-O-diphenylphosphono-3-O-[(R)-3-tetradecanoyloxytetradecanoyl]-6-O-(2,2,2-trichloro-1,1-dimethylethoxycarbonyl)-2-(2,2,2-trichlorethoxycarbonylamino)-β-D-glucopyranoside (compound 8) as a viscous oil: 1H NMR (CDCl3) δ 0.0 (s, 9 H), 0.8-1.0 (m, 8 H), 1.1-1.65 (m, 42 H), 1.83 and 1.90 (2s, 6 H), 2.15-2.45 (m, 4 H), 3.34 (q, 1 H, J=~8 Hz), 3.37 (m, 1 H), 3.81 (m, 1 H), 3.95 (m, 1 H), 4.27 (dd, 1 H, J=12, 5 Hz), 4.34 (d, 1 H, J=12 Hz), 4.58 (d, 1 H, J=12 Hz), 4.66 (q, 1 H, J=~9 Hz), 4.86 (d, 1 H, J=12 Hz), 5.03 (d, 1 H, J=7.9 Hz), 5.21 (m, 1 H), 5.54-5.70 (m, 2 H), 7.2-7.8 (m, 10 H).
