Acetoacetic Acid → 2-Bromo-5,6-dichloro-1-(5-deoxy-beta-D-ribofuranosyl)-1H-benzimidazole

Participants

Reaction Steps

2-Bromo-5,6-dichloro-1-(2,3-di-O-acetyl-5deoxy-beta-D-ribofuranosyl)-1H-benzimidazole (7.70 g, 16.52 mmol) was dissolved in ethanol (100 mL) and methanol (100 mL). A solution of sodium carbonate (1.75 g, 16.52 mmol) in water (30 mL) was added to the diacetate solution. The resulting mixture was stirred at rt for 17 h. The reaction mixture was concentrated, dissolved in ethyl acetate (125 mL) and extracted with water (3×50 mL). The ethyl acetate layer was dried with magnesium sulfate (anhyd), filtered, and evaporated. The crude residue was purified on a silica gel column with 1:30 methanol:CH—2Cl2. The resulting product was further purified on a silica gel column with 1:2 ethyl acetate: hexanes, followed by 1:1 ethyl acetate:hexanes to give the title compound (3.00 g, 7.85 mmol, 48%); MS (El): m/z (rel. intensity) 405 (0.05, M++Na); 1H NMR (DMSO-d6) δ8.00 (s, 1H, Ar—H), 7.87 (s, 1H, Ar—H), 5.87 (d, 1H, OH, J=6.7 Hz), 5.53 (d, 1H, OH, J=6.2 Hz), 5.29 (d, 1H, CH, J=5.1 Hz), 4.52 (m, 1H, CH), 4.01 (m, 1H, CH), 3.91 (m, 1H, CH), 1.42 (d, 3H, CH3, J=6.5 Hz).

Provenance & Evidence