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

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Reaction Conditions

Reaction Steps

To a suspension of 2,4-dibromo-5,6-dichloro-1H-benzimidazole (0.35 g, 1 mmol), in acetonitrile (5 mL) was added N,O-bis(trimethylsilyl)acetamide (0.25 mL, 1 mmol). The resulting mixture was allowed to stir at 70° C. for 15 min, followed by the addition of 1,2,3-tri-O-acetyl-5-deoxyribofuranose (0.31 g, 1.2 mmol) in acetonitrile (5 mL) and trimethylsilyltrifluoromethane sulfonate (0.25 mL, 1.3 mmol). The mixture was allowed to stir at 70° C. for 30 min and was then allowed to cool to RT. The mixture was diluted with ethyl acetate, washed with a saturated aqueous NaHCO3 solution, dried over NaSO4 and the solvents were removed by rotary evaporation. The product was purified by flash chromatography using methylene chloride then 1:1 methylene chloride/chloroform followed by recrystallization from methanol to provide 0.35 g (63%) of the title compound as white crystals: m.p. 152-154° C.; 1H NMR (DMSO-d6) δ: 8.16 (s, 1H), 6.15 (d, 1H), 5.63 (t, 1H), 5.27 (dd, 1H), 4.26 (m, 1H), 2.13 (s, 3H), 2.02 (s, 3H), 1.51 (d, 3H).

Provenance & Evidence