2-(2-fluoroethoxy)ethyl 4-methylbenzenesulfonate (52 mg, 0.19 mmol) dissolved in anhydrous DMF (3 mL) was added to a flask containing (2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-hydroxybenzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (intermediate D1) (57 mg, 0.15 mmol) in DMF (3 mL) at room temperature. Cesium carbonate (0.12 g, 0.36 mmol) was added to the flask, and the resulting mixture was stirred at room temperature for 48 hr. The reaction mixture was diluted with diethyl ether (50 mL) and the organic layer was washed with aqueous solutions of ammonium chloride (50 mL), sodium bicarbonate (50 mL), and NaCl (50 mL), followed by drying over sodium sulfate. The organic layer was concentrated in vacuo, followed by preparative TLC using 15% methanol in dichloromethane as the mobile phase to yield the title compound (4.5 mg, 5.0%). 1H NMR (CDCl3, 300 MHz): δ 7.30 (d, 1H, J=11.6 Hz), 7.17-7.12 (br m, 2H), 7.04 (d, 2H, J=11.6 Hz), 6.78 (d, 2H, J=11.6 Hz), 4.52 (dt, 2H, J1=5.6 Hz, J2=63.6 Hz), 4.33 (br s, 1H), 4.13 (br s, 1H), 4.04-3.96 (m, 4H), 3.81-3.67 (m, 5H), 3.63-3.49 (m, 2H), 3.38-3.21 (m, 3H), 2.78 (br s, 1H), 1.77 (br s, 2H); LC/MS: theoretical mass=470.15; observed M+1=471.6, M+Na=493.4).
