Trimethylsilyl triflate → 2,4,5,6-Tetrachloro-1-(2,3-di-O-acetyl-5-deoxy-beta-D-ribofuranosyl)-1H-benzimidazole

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Reaction Conditions

Reaction Steps

A mixture of 2,4,5,6-tetrachloro-1H-benzimidazole (1.02 g, 4.0 mmol), acetonitrile (20 mL), and N,O-bis(trimethylsilyl)acetamide (1.5 mL, 6 mmol) was stirred at 70° C. for 15 min. Then 1,2,3-tri-O-acetyl-5-deoxy-D-ribofuranose (1.35 g, 5.2 mmol) in acetonitrile (5 mL) was added, followed by trimethylsilyltrifluoromethane sulfonate (1.16 mL, 6.0 mmol). The resulting mixture was allowed to stir at 70° C. for 20 min. Another portion of 1,2,3-tri-O-acetyl-5-deoxy-D-ribofuranose (0.21 g, 0.8 mmol) in acetonitrile (2 mL) was added and stirring was continued at 70° C. for 10 min. The mixture was allowed to cool to RT and was diluted with ethyl acetate. The ethyl acetate layer was washed with a saturated NaHCO3/NaCl solution, dried over Na2SO4 and the solvents were removed by rotary evaporation. The product was purified by flash chromatography using chloroform as eluant. Recrystallization from methanol afforded 1.11 g (61 %) of the title compound as white crystals; m.p. 126-127° C.; 1H NMR (DMSO-d6) δ: 8.16 (s, 1H), 6.20 (d, 1H), 5.61 (t, 1H), 5.25 (dd, 1H), 4.24 (m, 1H), 2.13 (s, 3H), 2.02 (s, 3H), 1.50 (d, 3H).

Provenance & Evidence