p-Toluenesulfonic acid → [(1S,2S,3S,4R,5S)-2,3,4-tribenzyloxy-5-[4-chloro-3-[(4-ethoxyphenyl)methyl]phenyl]-7-methyl-6,8-dioxabicyclo[3.2.1]octan-1-yl]methanol

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Reaction Steps

To a solution of 1-[(2S,3S,4S,5R,6S)-3,4,5-tribenzyloxy-6-[4-chloro-3-[(4-ethoxyphenyl)methyl]phenyl]-2-(hydroxymethyl)-6-methoxy-tetrahydropyran-2-yl]ethanol 8b (0.6 g, 0.80 mmol) in dichloromethane (20 mL) was added p-toluenesulfonic acid (27.5 mg, 0.16 mmol). The mixture was stirred at room temperature for 2 hours and quenched with 5 mL of saturated aqueous sodium bicarbonate. The resulting mixture was partitioned. The aqueous layer was extracted with dichloromethane (10 mL×2). 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)=10/1 to give the title compound 8c as coloeless oil (258 mg, 44.8%). The compound was characterized by the following spectroscopic data: 1H NMR (400 MHz, CDCl3) δ (ppm): 7.41 (s, 1H), 7.34 (m, 4H), 7.31-7.27 (m, 6H), 7.24 (m, 2H), 7.14 (m, 3H), 7.06 (d, 2H), 6.89-6.83 (m, 2H), 6.77-6.72 (m, 2H), 4.86 (m, 3H), 4.74 (d, 1H), 4.32 (dd, 1H), 4.23 (d, 1H), 4.08 (m, 1H), 4.05-3.98 (m, 3H), 3.98-3.89 (m, 3H), 3.77 (d, 1H), 3.68 (d, 1H), 3.64 (d, 1H), 1.56 (d, 3H), 1.38 (t, 3H).

Provenance & Evidence