Ammonia → (2R,3R,4S,5R)-2-(2-amino-5,6-dichloro-benzimidazol-1-yl)-5-(hydroxymethyl)tetrahydrofuran-3,4-diol

Beteiligte Stoffe

Reaktionsschritte

2,5,6-Trichloro-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)benzimidazole (42, 0.48 g; 1 mmole) was dissolved in dry MeOH (10 ml). Liq. NH3 (10 ml) was added and the mixture heated in a steel bomb at 100° C. for 2 hr. This mixture was stirred at room temperature for 24 hr. Excess NH3 was allowed to evaporate and the solution evaporated to dryness, absorbed onto silica gel (2 g), and chromatographed on a silica gel column using silica gel (20 g; 60-200 mesh). Elution of the column with CH2 Cl2 : CH3OH (96:4) gave the desired compound 44 as the major nucleoside. Evaporation of the solvent and crystallization of the residue from EtOH gave 44 (0.02 g; yield 6.06%). mp. 145° C.; UV Imax. (MeOH): 259 (7941) and 301 (8348) nm; Imax (pH1): 215 (26000) and 292 (7520) nm; Imax (pH11): 257 (7967) and 298 (7107) nm. 1H NMR(DMSO-d6): d 8.70 (s, 1H, C7 -H, 8.28(s,1H, C4 -H), 7.90 (bs,2H, D2O exchangeable, NH2), 6.75(d,C1'H, J1,2 =4.5 Hz) and the rest of the sugar protons.

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