Reaction Steps
To a mixture of (3S,4S,5R)-6-(acetoxymethyl)tetrahydro-2H-pyran-2,3,4,5-tetrayl tetraacetate (1.0 g, 2.56 mmol, mixture of 2-α and 2-β), 4-methoxytoluene (0.65 mL, 5.12 mmol) and silver trifluoroacetate (0.85 g, 3.84 mmol) in dichloromethane (5.0 mL) at room temperature was added a solution of tin(IV) chloride (7.7 mL, 1.0 M in dichloromethane) dropwise. The reaction solution was stirred under nitrogen for 4 hours and then it was quenched with aqueous sodium bicarbonate and extracted with ethyl acetate (3×). The combined organic extract was washed with brine, dried over sodium sulfate and concentrated in vacuo. The crude product was purified by flash column chromatography (eluent: hexanes/ethyl acetate) to give (3R,4R,5R,6S)-2-(acetoxymethyl)-6-(2-methoxy-5-methylphenyl)tetrahydro-2H-pyran-3,4,5-triyl triacetate (0.88 g, 76%) as a orange oil: 1H NMR (CDCl3, 500 MHz) δ 7.18 (d, J=2.0 Hz, 1H), 7.07-7.05 (m, 1H), 6.75 (d, J=8.5 Hz, 1H), 5.35 (t, J=9.5 Hz, 1H), 5.28 (t, J=9.0 Hz, 1H), 5.23 (t, J=9.5 Hz, 1H), 4.92 (d, J=9.5 Hz, 1H), 4.28 (dd, J=12.5, 5.0 Hz, 1H), 4.14 (dd, J=12.0, 2.5 Hz, 1H), 3.84 (ddd, J=10.0, 5.0, 2.5 Hz, 1H), 3.80 (s, 3H), 2.28 (s, 3H), 2.08 (s, 3H), 2.05 (s, 3H), 2.00 (s, 3H), 1.77 (s, 3H).
