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

Participants

Reaction Conditions

Reaction Steps

To a solution of [(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 28h (4.09 g, 6.2 mmol) in an anhydrous methanol/tetrahydrofuran mixture (v/v=3/1, 20 mL) was added sodium borohydride (278 mg, 7.5 mmol) at 0° C. The mixture was stirred at 0° C. for 5 min, then quenched with water at 0° C. and adjusted with saturated aqueous ammonium chloride till pH becomes 7. The mixture was concentrated in vacuo to remove parts of the solvent. The resulting mixture was extracted with ethyl acetate (100 mL×3). The combined organic layers were washed with saturated aqueous sodium chloride (100 mL×3), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated in vacuo to give the title compound 28i as pale yellow oil (4.08 g, 100%). The compound was characterized by the following spectroscopic data: 1H NMR (400 MHz, DMSO-d6) δ (ppm): 7.50 (m, 2H), 7.38 (d, 3H), 7.30 (m, 3H), 7.21 (m, 3H), 7.03 (d, 2H), 6.80 (d, 2H), 6.74 (d, 2H), 5.17 (d, 1H), 4.75 (d, 1H), 4.52 (d, 1H), 4.41 (d, 1H), 4.34 (d, 1H), 4.27 (d, 1H), 4.13 (d, 1H), 3.99 (m, 2H), 3.94 (m, 3H), 3.85 (m, 3H), 3.71 (d, 1H), 2.01 (s, 3H), 1.28 (t, 3H).

Provenance & Evidence