2 inverted exclamation marka-Deoxy-|A-L-uridine → 1-(5-o-Tert-butyldiphenylsilyl-2-deoxy-beta-l-threo-pentofuranosyl)uracil

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Reaction Steps

Tert-butyldiphenylsilane chloride (0.9 ml; 3.50 mmol) is added to a solution of 7a (0.6 g; 2.63 mmol) in anhydrous pyridine (8 ml). The solution is stirred for 4 h at room temperature and then the solvent is evaporated under reduced pressure. Water and dichloromethane are added. The organic phase is separated, washed successively with a saturated aqueous sodium hydrogen carbonate solution and water, dried over sodium sulfate and filtered. After evaporation to dryness, the residue is chromatographed on a silica gel column [eluent: step gradient of methanol (0-2%) in dichloromethane] to give 1.2 g (98%) of 8a in the form of a foam: 1H NMR (DMSO-d6) δ ppm: 11.26 (s, 11H, 3-NH), 7.78 (d, 1H, H-6; J=8.2 Hz), 7.65-7.35 (m, 10 H, 2 C6H5), 6.09 (dd, 1H, H-1′; J=1.9 and 6.4 Hz), 5.55 (d, 1H, H-5; J=8.2 Hz), 5.30 (d, 1H, OH-3′: J=3.1 Hz), 4.25 (m, H, H-3′), 4.05-3.95 (m, 2H, H-4′ and 5′), 3.85-3.80 (m, 1H, H-5″), 2.6-2.5 (m, 1H, H-2′ partially obscured by DMSO-d5), 1.85 (dd, 1H, H-2″; J=1.9 and 16.5 Hz), 0.93 [s, 9H, (CH3)3C]; mass spectrum (matrix: glycerol-thioglycerol: 50:50, v/v): FAB<0 465 [M−H]− and 111 [B]−.

Provenance & Evidence