Reaction Steps
To a stirred solution of the product from step B (470 mg, 0.98 mmol) and triethylamine (0.54 mL, 3.90 mmol) in toluene/ethyl acetate (1:1, 12 mL) at 0° C. was added dropwise methanesulfonyl chloride (0.15 mL, 1.95 mmol). The reaction mixture was stirred at 0° C. for 2 h. The white precipitate formed during the reaction was filtered off and washed with ethyl acetate. The combined filtrate and washing were concentrated. The residual oil was dissolved in acetone (6 mL) and treated with lithium bromide (850 mg, 10.0 mmol) at 0° C. After stirring at room temperature for 1 h, the reaction was quenched with water (25 mL) and extracted with ethyl acetate (4×). The combined extracts were dried over sodium sulfate, filtered, and concentrated to give compound (2S,3R,4S,5R)-2-(3-(bromomethyl)-4-chlorophenyl)-3,4,5-tris(methoxymethoxy)-6-((methoxymethoxy)methyl)tetrahydro-2H-pyran (517 mg, 97%) as a white solid: 1H NMR (CDCl3, 500 MHz) δ 7.46 (d, J=2.0 Hz, 1H), 7.37 (d, J=8.3 Hz, 1H), 7.30 (dd, J=8.3, 2.0 Hz, 1H), 4.91 (d, J=6.4 Hz, 1H), 4.89-4.86 (m, 2H), 4.77 (d, J=6.4 Hz, 1H), 4.66 (s, 2H), 4.60-4.55 (m, 2H), 4.54 (d, J=6.4 Hz, 1H), 4.17 (d, J=9.4 Hz, 1H), 4.13 (d, J=6.5 Hz, 1H), 3.92 (dd, J=11.2, 1.6 Hz, 1H), 3.75 (t, J=8.8 Hz, 1H), 3.71 (dd, J=11.2, 5.2 Hz, 1H), 3.63-3.58 (m, 2H), 3.52 (t, J=9.3 Hz, 1H), 3.450 (s, 3H), 3.446 (s, 3H), 3.34 (s, 3H), 2.79 (s, 3H); ESI MS m/z 543 [M+H]+.
