To a stirred suspension of (2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-hydroxybenzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (intermediate D1) (100 mg, 0.26 mmol) in N,N-dimethylformamide (3 mL) and cesium carbonate (162 mg, 0.52 mmol) was added 1-bromo-2-(2-bromoethoxy)ethane (182 mg, 0.79 mmol). The mixture was stirred overnight at room temperature. The solution was diluted with water and the aqueous layer was extracted with ethyl acetate. The combined organic layers were concentrated under reduced pressure. The residue was purified by preparative TLC to give 30 mg of yellow oil (21% yield), which was used in the next step without purification.
