beta-D-Ribofuranose, 1-acetate 2,3,5-tribenzoate → (2R,3S,4R,5R)-2-(hydroxymethyl)-5-(2,5,6-trichlorobenzimidazol-1-yl)oxolane-3,4-diol

Participants

Reaction Conditions

Reaction Steps

2,5,6-Trichlorobenzimidazole (700 mg, 0.0032 moles) was dissolved in acetonitrile and BSTFA (1 ml, 0.0038 moles) was added. The mixture was heated at 75° C. for 20 minutes. TMSTf (1 ml, 0.0051 moles) and 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (1.9 g, 0.0038 moles) were added while heating was continued for 45 min. The acetonitrile was removed under reduced pressure and the protected nucleoside was separated on a silica column, eluting with chloroform. The benzoyl protecting groups were removed by overnight treatment at room temperature with methanolic ammonia. The nucleoside was separated on a column using 50% EtOAc/hexane and then 10% MeOH/CHCl3. The isolated compound was recrystallized from methanol. Yield: (74%); MP: 185°-186° C.; TLC (10% MeOH/CHCl3): Rf=0.20; 1H NMR (DMSO-d6) δ3.68 ppm (q, 2H), 4.00 (d, 1H), 4.12 (t, 1H), 4.40 (q, 1H), 5.28 (d, 1H), 5.41 (t, 1H), 5.49 (d, 1H), 5.57 (d, 1H), 7.96 (s, 1H), 8.55 (s, 1H); 13C NMR (DMSO-d6, Broad band decoupling): d 61.08 ppm, 69.80, 71.70, 86.47, 89.16, 114.93, 120.04, 125.77, 125.97, 132.30, 140.96, 142.16; MS (Fast Atom Bombardment): m/e (M+ 6) 359, (M+ 4) 357, (M+ 2) 355, (M+) 353, 319, 285, 263, 221, 187, 177, 133, 115, 103, 97, 85.

Provenance & Evidence