Trimethylsilyl triflate → HCID 10813653, compound

Participants

Reaction Conditions

Reaction Steps

To a suspension of 3.952 g (20 mmole) of 19 in 100 mL of 1,2-dichloroethane, was added 5 mL (20 mmole) of BSA. The reaction mixture was stirred at 75° C. for 15 min to give a clear solution. This solution was cooled to ~20° C. and treated with 7.0 g (22 mmole) of 1,2,3,5-tetra-O-acetyl-b-D-ribofuranose and 4.638 mL (24 mmole) of TMSOTf at room temperature for 2 h. The reaction mixture was diluted with 200 mL of CHCl3. The CHCl3 solution was washed with sat. NaHCO3 solution (200 mL×2), sat. NaCl solution (200 mL), dried (Na2SO4), and evaporated. The residue was chromatographed on a silica column (5×35 cm, eluted with CHCl3 and 0.5% MeOH/CHCl3). Evaporation of the appropriate fractions gave 6.50 g (71%, one spot on TLC) of 74 and 75 as a white foam. Fractional recrystallization of this foam (5 times from MeOH) give 1.59 g (17%) of the pure 6-nitro isomer 75. MP 127°-129° C. MS (El) m/e 455.0750 (2%, M+ =455.0732). 1H NMR (DMSO-d6): d 8.68 (d, 1, 7-H, J7-5 =2.0 Hz), 8.21 (dd, 1, 5-H, J5-4 =9.0 Hz), 7.88 (d, 1, 4-H), 6.41 (d, 1, 1'-H, J1'-2' =7.0 Hz), 5.58 (t, 1, 2'-H, J2'-3' =7.0 Hz), 5.45 (dd, 1, 3'-H, J3'-4' =4.0 Hz), 4.50, 4.40 (2×m, 3, 4'-H and 5'-H), 215, 2.12, 2.03 (3×s,9, 3×Ac). 13C NMR (DMSO-d6): d 170.12, 169.49, 169.25 (3×OCOCH3), 145.60 (C3a), 143.96 (C2), 143.65 (C6), 132.46 (C7a), 119.65 (C4), 118.92 (C5), 108.47 (C7), 86.96 (C1'), 79.67 (C4'), 71.12 (C2'), 68.75 (C3'), 62.56 (C5'), 20.39, 20.31, 20.03 (3×OCOCH3).

Provenance & Evidence