Trimethylsilyl triflate → 2-Chloro-5,6-dinitro-1-(2,3,5-tri-O-benzyl-beta-D-ribofuranosyl)benzimidazole

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a mixture of 0.541 g (2.23 mmol) of 2-chloro-5,6-dinitrobenzimidazole in 12 mL of MeCN, was added 0.558 mL (2.23 mmol) of BSA. The reaction mixture was stirred at 75° C. for 15 min to give a clear solution. This solution was treated with the above MeCN solution of 2,3,5-tri-O-benzyl-D-ribofuranosyl chloride and 0.56 mL (2.90 mmol) of TMSOTf at 75° C. for 30 min. The reaction mixture was cooled and diluted with EtOAc (50 mL). The EtOAc solution was washed with sat. NaHCO3 solution (50 mL×2), sat. NaCl solution (50 mL), dried (Na2SO4), and evaporated. The residue was chromatographed on a silica column (2.2×18 cm, eluted with 20% EtOAc/hexane). Evaporation of fractions 10-14 (20 mL per fraction) gave 0.502 g (35%) of 60 as a syrup. MS: (FAB) m/e 645 (1%, MH+ =645). 1H NMR (DMSO-d6): δ8.50, 8.49 (2×s, 2, 7-H and 4-H), 7.34, 6.90 (2×m, 15, 3×Ph), 6.09 (d, 1, 1'-H, J1'-2' =8.0 Hz), 4.73~4.27 (m, 9, 2'-H, 3'-H, 4'-H, and 3×PhCH2), 3.77 (dd, 1, 5'-H, J4'-5' =2.0 Hz, J5'-5" =11.0 Hz), 3.65 (dd, 1, 5"-H, J4'- 5" =2.5 Hz).

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