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

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Reaction Steps

To a stirred solution of Na2CO3 (0.325 g, 3 mmol) in H2O (10 mL), were added successively 45 mL of EtOH, 45 mL of MeOH, and 0.46 g (1 mmol) of 2b. Stirring was continued at room temperature for 2 h. The reaction mixture was neutralized with glacial AcOH and then concentrated to about 10 mL. The yellow, oily residue was triturated with H2O (10 mL) and the resulting yellow precipitate was collected by filtration. This precipitate was dissolved in EtOH, decolorized with charcoal, and recrystallized from H2O/EtOH/dioxane. Final recrystallization from H2O gave 0.206 g (61 %) of 4a. MP: 85-86° C. MS: (EI, with DCI probe) m/z 336 (4, M+=336). 1H NMR (DMSO-d6): δ7.99 (s, 1, 4-H), 7.89 (s, 1, 7-H), 5.87 (d, 1, 1-H, J1′-2′=6.5 Hz), 5.53 (d, 1, 2′-OH, J2′-2′=6.0 Hz), 5.28 (d, 1, 3′-OH, J3′-3′OH=5.0 Hz), 4.49 (m, 1, 2′-H, J2′-3′=6.0 Hz), 4.00 (M, 1, 4′-H, J3′-4′=4.0 Hz, J4′-5′=6.5 Hz), 3.89 (m, 1, 3′-H), 1.41 (d, 3, 5′-H). 13C NMR (DMSO-d6): δ142.09 (C2), 141.03 (C3a), 132.68 (C7a), 126.14, 125.93 (C5 and C6), 120.40 (C4), 113.42 (C7), 90.02 (C1′), 80.97 (C4′), 73.80 (C3′), 71.71 (C2′), 18.88 (C5′). Anal. (C12H11Cl3N2O3) C, H, N.

Provenance & Evidence