Reaction Steps
To a solution of (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl (1S,2R)-3-[(1,3-benzodioxol-5-ylsulfonyl)(isobutyl)amino]-2-hydroxy-1-(4-hydroxybenzyl)propylcarbamate (0.6 g, 1.01 mmol), triphenyl phosphine (0.4 g, 1.52 mmol), and 4-{[tert-butyl(dimethyl)silyl]oxy}-1-butanol (0.31 g, 1.52 mmol, J. Org. Chemn. 1986, 51, 3388-3390) in anhydrous dichloromethane (9 mL) at 0° C. under nitrogen atmosphere was slowly added a solution of diisopropyl azodicarboxylate (0.29 mL, 0.3 g, 1.52 mmol) in anhydrous dichloromethane (2 mL) and the mixture was stirred at ambient temperature for 2 h. Solvent was evaporated and the residue was purified by chromatography (silica gel, hexanes/ethyl acetate, 1:1) to provide the title compound as a solid foam (0.39 g). 1H NMR (DMSO-d6): δ 0.0 (6H, s), 0.78 (3H, d), 0.80 (3H, d), 0.82 (9H, s), 1.22 (1H, dd), 1.4 (1H, quintuplet), 1.55 (2H, quintuplet), 1.7 (2H, quintuplet), 1.8-1.9 (1H, m), 2.35 (1H, t), 2.65-2.80 (3H, m), 2.9 (1H, d), 3.0 (1H, dd), 3.2-3.3 (2H, m), 3.4-3.5 (1H, m), 3.52-3.62 (4H, m), 3.7 (1H, t), 3.8 (1H, dd), 3.9 (2H, t), 4.8 (1H, dt), 5.0 (1H, br s), 5.5 (1H, d), 6.18 (2H, s), 6.77 (2H, d), 7.0-7.1 (3H, m), 7.19 (1H, d), 7.21 (1H, s), 7.3 (1H, d); MS: 801 (M+23); C38H58N2O11SSi.
