Reaction Steps
2,4,6-Triisopropyl benzenesulfonyl chloride (581 mg, 1.92 mmol) was added to a solution of compound 65 (400 mg, 0.48 mmol), DMAP (64 mg, 0.53 mmol), and triethylamine (0.60 mL, 4.32 mmol) in anhydrous CH2Cl2 (15 mL). The mixture was stirred at room temperature overnight under a nitrogen atmosphere, concentrated in vacuo, and the residue was dissolved in a solution of NH3 in 1,4-dioxane (0.5 M, 20 mL). The mixture was transferred into a sealed tube and was heated at 90° C. overnight. The reaction was then cooled to room temperature, concentrated in vacuo, and the residue was dissolved in THF (8.0 mL) followed by addition of n-Bu4NF (333 mg, 1.06 mmol). The mixture was stirred at room temperature for four hours, concentrated in vacuo, and the residue was purified by silica gel column chromatography to yield 5-[(S)-1-(4-iodo-5-methoxy-2-nitrophenyl)-2,2-dimethyl-propyloxy]methyl-2′-deoxycytidine 66 (240 mg, 83% for three steps in total). 1H NMR (400 MHz, MeOD-d4): δ 8.33 (s, 1H, Ph-H), 7.91 (s, 1H, H-6), 7.10 (s, 1H, Ph-H), 6.16 (t, 1H, J=6.4 Hz, H-1′), 5.19 (s, 1H, Ph-CH), 4.41 (d, 1H, J=12.4 Hz, 5-CH2a), 4.33 (m, 1H, H-3′), 4.26 (d, 1H, J=12.4 Hz, 5-CH2b), 3.97 (s, 3H, OCH3), 3.88 (m, 1H, H-4′), 3.70 (m, 2H, H-5′), 2.34 (m, 1H, H-2′a), 2.17 (m, 1H, H-2′b), 0.84 (s, 9H, C(CH3)3).
