Acetic Anhydride → 1-[5-O-Acetyl-2-deoxy-3-O-(t-butyldimethylsilyl)-4-ethynyl-beta-D-threo-pentofuranosyl]thymine

Participants

Reaction Steps

To a pyridine (4 mL) solution of 10a (161 mg, 0.423 mmol) was added Ac2O (120 mL, 1.269 mmol) at 0° C., and the mixture was stirred at room temperature for 11 h. The reaction mixture was partitioned between CHCl3/saturated aqueous NaHCO3 (60 mL×3/20 mL). Silica gel column chromatography (hexane/EtOAc=3/1) of the organic layer gave 11 (169.7 mg, 95%) as a foam: UV (MeOH):λmax 266 nm (ε9200),λmin 234 nm (E2000); 1H NMR(CDCl3)δ0.10 and 0.14 (6H, each as s, SiMe), 0.90 (9H, s, SiBu-t), 1.90-1.94 (4H, m, H-2′a and Me), 2.14 (3H, s, Ac), 2.58 (1H, s, ethynyl), 3.01 (1H, ddd, Jgem=14.8 Hz, J1′,2′b=8.3 Hz and J2′b,3′=5.0 Hz, H-2′b), 4.37 (1H, d, Jgem=11.1 Hz, H-5′a), 4.45 (1H, d, J2′b,3!=5.0 Hz, H-3′), 4.53 (1H, d, Jgem=11.1 Hz, H-5′b), 6.40 (1H, dd, J1′,2′a=2.8 Hz and J1′,2′b=8.3 Hz, H-1′), 7.53 (1H, d, J6,Me=1.3 Hz, H-6), 8.04 (1H, br, NH); FAB-MS m/z 461 (M++K). Anal. Calcd for C20H30N2O6Si: C, 56.85; H, 7.16; N, 6.63. Found: C, 56.84; H, 7.35; N, 6.26.

Provenance & Evidence