To 0.5580 g N4-benzoyl-3′-O-(methylthlomethyl)-5′-O-(tert-butyldimethylsilyl)-2′-deoxycytidine (6c) (1.04 mmol) dissolved in 8 mL dry CH2Cl2 were added 0.56 mL cyclohaxene and 220 μL SO2C2 (2.7 mmol) at 0° C. and stirred at the ice-cold temperature for 1 h. During this time, the starting material converted to the chlorinated product as shown by the 3′-OH (5c) compound in the TLC. The volatiles were then removed under vacuum and resuspended in dry DMF (5 mL) and treated with NaN3 (400 mg, 6.6 mmol) and stirred for 2 h at room temperature. The sample was then partitioned between water and CH2Cl2 and the organic extracts were combined and dried over Na2SO, and concentrated under vacuum. The crude sample was then dissolved in MeOH (5 mL) and treated with NH4F (600 mg, 16.2 mmol) for 20 h at room temperature. Then solvent was removed under vacuum and extracted with CH2Cl2 and the organic extract was then dried over Na2SO4 and concentrated under vacuum. The sample was then purified by silica gel column chromatography (Hex:EtOAc 1:4 to 1:10), and the product (9c) was obtained as white powdery substance (˜200 mg, 50% yield in three steps, Rf=0.5, EtOAc:Hex/5:0.5). HR-MS: Obs. m/z 387.1408, calcd for C17H19O5N6 387.1417 [M+H]+. 1H-NMR (CDC3): δH 8.30 (d, J=7.2 Hz, 1H), 7.93 (d, J=7.50 Hz, 1H), 7.66-7.51 (m, 5H), 6.18 (t, J=6.4 Hz, 1H), 4.81-4.68 (m, 2H), 4.52 (m, 1H), 4.25 (m, 1H), 4.08-3.88 (m, 2H), 2.69 (m, 1H), and 2.50 (m, 2H) ppm.
