Reaction Steps
A solution of 36 (2.9 g, 5.8 mmol), sodium azide (1.89 g, 29.1 mmol) and nBu4NI (4.3 g, 11.6 mmol) in anhydrous DMF (20 mL) was stirred at 90° C. for 24 h. The solution was cooled to rt then diluted with EtOAc (300 mL). The organic layer was washed with water (3×200 mL), dried (Na2SO4), filtered and evaporated. The oily residue was purified by flash silica gel column chromatography (PE then PE/EtOAc 1:1) to afford 37 (2.54 g, 86%) as a pale yellow oil. 1H NMR (CDCl3, 300 MHz): δ 1.96, 2.02, 2.08, 2.13 (4s, 4×3H, 4×CH3CO), 3.37 (t, 2H, J=5.0 Hz, CH2N3), 3.60-3.72 (m, 9H, OCH2CH2O), 3.74-3.84 (m, 1H, OCH2), 4.00-4.15 (m, 2H, H-5, H-6), 4.27 (dd, 1H, J6′,5=5.1 Hz, J6′,6=12.4 Hz, H-6′), 4.85 (d, 1H, J1,2=1.5 Hz, H-1), 5.20-5.37 (m, 3H, H-2, H-3, H-4). 13C NMR (CDCl3, 75 MHz): δ 20.62, 20.63, 20.7, 20.8 (4s, 4×CH3CO), 50.6 (CH2N3), 62.3 (C-6), 66.0, 68.3, 69.0, 69.5 (4s, C-2 to C-5), 67.2, 69.97, 70.02, 70.6, 70.7 (5s, 5×CH2O), 97.6 (C-1), 169.6, 169:8, 170.0, 170.6 (4s, 4×CH3CO)-[α]D=+34 (c=1/CH2Cl2). ESIMS (positive mode) m/z: 528 [M+Na]+. HRESIMS (positive mode) m/z: calcd for C20H31N3O12Na1 [M+Na]+ 528.1805. found 528.1801.
