(3R,4R,5S,6R)-2-(4-chloro-3-(4-hydroxybenzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (intermediate D) (30 mg, 78.7 mmol), 2-(2-(tert-butoxycarbonylamino)ethoxy)ethyl methanesulfonate (26.8 mg, 94.5 mmol) and Cs2CO3 (30.8 mg, 94.5 mmol) were dissolved in DMF (3 ml) at room temperature and stirred overnight. The mixture was then extracted with EtOAc, washed with NH4Cl and NaCl, dried over Na2SO4, and evaporated to get the crude product, tert-butyl 2-(2-(4-(2-chloro-5-((2S,3R,4R,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)benzyl)phenoxy)ethoxy)ethylcarbamate (intermediate U) (40 mg), which was used for the next step without further purification. The crude intermediate U was dissolved in MeOH (0.5 mL), MeSO3H (6 μL) was added, and the mixture was stirred overnight at room temperature. Then the reaction was quenched with NaHCO3, the mixture was extracted with ethyl acetate, and the organic layer was washed with brine, dried over Na2SO4, concentrated, and separated by preparative HPLC to obtain compound V (11.6 mg). 1H NMR (CD3OD): δ 7.40˜7.27 (m, 3H), 7.14˜7.10 (m, 2 H), 6.87˜6.85 (m, 2 H), 4.54 (d, J=16, 1H), 4.19˜4.18 (m, 1H), 4.16˜4.14 (m, 2H), 4.05˜4.01 (m, 4 H), 3.94˜3.93 (m, 1H), 3.88˜3.86 (m, 2H), 3.83˜3.76 (m, 3H), 3.67˜3.57 (m, 1H), 3.16˜3.13 (m, 2 H); MS ESI (m/z): 468 (M+H)+, calc. 467.
