(1S,2S,3S,4R,5S)-2,3,4-tribenzyloxy-5-[4-chloro-3-[(2,3-difluoro-4-methoxy-phenyl)methyl]phenyl]-6,8-dioxabicyclo[3.2.1]octane-1-carbaldehyde → HCID 131736389, compound

To a solution of (1S,2S,3S,4R,5S)-2,3,4-tribenzyloxy-5-[4-chloro-3-[(2,3-difluoro-4-methoxy-phenyl)methyl]phenyl]-6,8-dioxa bicyclo[3.2.1]octane-1-carbaldehyde 21p (0.50 g, 0.69 mmol) in dry tetrahydrofuran (10 mL) was added dropwise methylmagnesium bromide (0.46 mL, 1.38 mmol, 3M in ethyl ether) under N2 at 0° C. The mixture was stirred at room temperature for 2 hours and quenched with water (10 mL). The resulting mixture was extracted with ethyl acetate (10 mL×3). The combined organic layers were washed with saturated aqueous sodium chloride (15 mL), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated in vacuo and the residue was purified by silica gel chromatography eluted with PE/EtOAc(v/v)=15/1 to give the title compound 21q as a white solid (0.14 g, 19%). The compound was characterized by the following spectroscopic data: 1H NMR (400 MHz, CDCl3) δ(ppm): 7.41 (s, 3H), 7.31 (m, 9H), 7.21 (m, 4H), 6.98-6.86 (m, 2H), 6.68 (m, 1H), 6.53 (m, 1H), 4.96 (m, 2H), 4.80 (m, 2H), 4.34-4.24 (m, 2H), 4.16-4.05 (m, 4H), 3.98 (m, 2H), 3.85 (s, 3H), 3.82 (dd, 1H), 3.70 (m, 1H), 1.27 (d, 3H).