Reaction Steps
Step-X: To a stirred solution of acetic acid (3S,4R,5S,6S)-3,4,5-triacetoxy-6-[4-cyclopropyl-3-(2,3-dihydro-benzo[1,4]dioxin-6-ylmethyl)-phenyl]-tetrahydro-pyran-2-yl ester (1.9 g, 3.3 mmol) in dioxane (8 ml) was added thiourea followed by trimethylsilyl trifluoromethane sulfonate (0.88 ml, 4.8 mmol). The reaction mixture was heated to 80° C. for 3 h. Reaction mixture was cooled to room temperature and added methyl iodide (0.52 ml, 8.1 mmol) followed by diisopropylethyl amine (2.79 ml, 16.2 mmol) and stirred for additional 3 h. Reaction mixture was diluted with ethyl acetate (40 ml) and washed with water (40 ml). The organic layer was concentrated. The resulting residue was taken in methanol (10 ml) and heated to 60° C. for 2 h, then cooled to 0° C. and stirred for additional 1 h. The resulting solid was filtered and washed with methanol to give 750 mg of acetic acid (3S,4R,5S,6S)-4,5-diacetoxy-6-[4-cyclopropyl-3-(2,3-dihydro-benzo[1,4]dioxin-6-ylmethyl)-phenyl]-2-methylsulfanyl-tetrahydro-pyran-3-yl ester. 1H NMR (400 MHz, DMSO-d6): δ 0.55-0.59 (m, 2H), 0.85 (d, J=8.8 Hz, 2H), 1.70 (s, 3H), 1.82-1.89 (m, 1H), 1.93 (s, 3H), 2.03 (s, 3H), 2.08 (s, 3H), 3.95 (d, J=15.2 Hz, 1H), 4.02 (d, J=16.8 Hz, 1H), 4.00 (s, 4H), 4.65 (d, J=10.0 Hz, 1H), 4.87 (d, J=10.0 Hz, 1H), 5.03-5.12 (m, 2H), 5.34 (t, J=10.0 Hz, 1H), 6.58-6.60 (m, 2H), 6.73 (d, J=7.6 Hz, 1H), 6.91 (d, J=8.0 Hz, 1H), 7.04 (d, J=8.0 Hz, 1H), 7.15 (d, J=8.0 Hz, 1H). MS (ES) m/z 588.3 (M+18).
