Reaction Steps
To a solution of (1S,2S,3S,4R,5S)-2,3,4-tribenzyloxy-5-[4-chloro-3-[(4-ethoxyphenyl)methyl]phenyl]-6,8-dioxabicyclo[3.2.1]octane-1-carbaldehyde 1k (0.2 g, 0.28 mmol, obtained from the synthetic method described in step 10 of example 1) in anhydrous tetrahydrofuran (10 mL) was added dropwise 1-propynylmagnesium bromide (1.1 mL, 0.57 mmol, 0.5 M in tetrahydrofuran) at 0° C. After the addition, the mixture was stirred at room temperature for 4 hours and quenched with 1.5 mL of saturated aqueous ammonium chloride. The resulting mixture was extracted with ethyl acetate (20 mL×3). The combined organic layers were washed with water (10 mL×2) and then saturated aqueous sodium chloride (10 mL×2), dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was purified by silica gel chromatography eluted with PE/EtOAc(v/v)=8/1 to give the title compound 5a as colorless oil (145 mg, 69%). The compound was characterized by the following spectroscopic data: 1H NMR (400 MHz, CDCl3) δ(ppm:) 7.45 (m, 1H), 7.37 (m, 2H), 7.32 (m, 8H), 7.28 (m, 2H), 7.16 (m, 3H), 7.07 (d, 2H), 6.88 (m, 2H), 6.74 (m, 2H), 4.90 (m, 1H), 4.85 (m, 1H), 4.81 (m, 1H), 4.57 (m, 1H), 4.37 (t, 1H), 4.29 (m, 1H), 4.23 (m, 1H), 4.17 (m, 1H), 4.09 (m, 1H), 4.02 (m, 2H), 3.96 (m, 3H), 3.84 (d, 1H), 3.73 (d, 1H), 2.35 (d, 1H), 1.84 (s, 3H), 1.38 (t, 3H).
