Acetic Anhydride → [(1R,3R,4R,5S)-3,4-dibenzyloxy-5-[4-chloro-3-[(4-ethoxyphenyl)methyl]phenyl]-2-oxo-6,8-dioxabicyclo[3.2.1]octan-1-yl]methyl acetate

Participants

Reaction Steps

To a solution of (1S,3R,4R,5S)-3,4-dibenzyloxy-5-[4-chloro-3-[(4-ethoxyphenyl)methyl]phenyl]-1-(hydroxymethyl)-6,8-dioxabicyclo[3.2.1]octan-2-one 28g (13.4 g, 21.8 mmol) in dichloromethane (40 mL) were added acetic anhydride (3.0 mL, 32.7 mmol) and triethylamine (6.0 mL, 43.6 mmol) at room temperature. The mixture was stirred at room temperature for 2 hours and quenched with water (100 mL). The resulting mixture was extracted with dichloromethane (100 mL×2). The combined organic phases were washed with saturated aqueous sodium chloride (100 mL×3), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated in vacuo. The residue was purified by silica gel chromatography eluted with PE/EtOAc(v/v)=10/1 to give the title compound 28h as a pale yellow solid (12.1 g, 84.6%). The compound was characterized by the following spectroscopic data: 1H NMR (600 MHz, CDCl3) δ (ppm): 7.29 (m, 4H), 7.24 (m, 3H), 7.19 (s, 1H), 7.12 (d, 1H), 7.07 (m, 2H), 6.99 (d, 2H), 6.76 (m, 2H), 6.68 (d, 2H), 4.94 (d, 1H), 4.58 (d, 1H), 4.47 (d, 1H), 4.37 (d, 1H), 4.31 (m, 2H), 4.07 (d, 1H), 3.95 (m, 3H), 3.88 (m, 5H), 1.97 (s, 3H), 1.31 (t, 3H).

Provenance & Evidence