Methanol → methyl(1S,2S,3S,4R,5S)-2,3,4-tribenzyloxy-5-[4-chloro-3-[[4-(trifluoro methoxy)phenyl]methyl]phenyl]-6,8-dioxabicyclo[3.2.1]octane-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of (1S,2S,3S,4R,5S)-2,3,4-tribenzyloxy-5-[4-chloro-3-[[4-(trifluoromethoxy) phenyl]methyl]phenyl]-6,8-dioxabicyclo[3.2.1]octane-1-carboxylic acid 16a (0.49 g, 0.64 mmol) in tetrahydrofuran (2 mL) were added methanol (8 mL) and concentrated sulphuric acid (0.24 mL) at room temperature. The mixture was stirred at 45° C. for 20 hours. The reaction mixture was neutralized with saturated aqueous sodium bicarbonate till pH becomes 7 and extracted with ethyl acetate (10 mL×3). The combined organic layers were washed with saturated aqueous sodium chloride (10 mL×2), 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)=20/1 to give the title compound 16b as a white solid (322 mg, 66.5%). The compound was characterized by the following spectroscopic data: 1H NMR (400 MHz, CDCl3) δ(ppm): 7.48 (d, 1H), 7.44-7.38 (m, 2H), 7.32 (m, 7H), 7.26 (m, 3H), 7.21 (d, 1H), 7.16 (m, 4H), 7.05 (d, 2H), 6.87 (d, 2H), 4.90-4.81 (m, 2H), 4.79 (d, 1H), 4.63 (d, 1H), 4.53 (d, 1H), 4.32 (d, 1H), 4.20 (dd, 2H), 4.10 (t, 2H), 4.02 (dd, 1H), 3.89 (d, 1H), 3.74 (d, 1H), 3.71 (s, 3H).

Provenance & Evidence