Reaction Steps
(−)-N4-Benzoyl-1-[(1S,2S,4R)-5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-2-phenylselenyl-4-thio-β-L-ribofuranosyl]-5-fluorocytosine (L-10, FIG. 4a) was made using the general procedure for condensation reaction of the acetate L-8 with pyrimidines. The compound L-10 was obtained on 0.849-mmol scale in 59% yield: [α]24D −209.1° (c 0.693, CH2Cl2); UV(CH2Cl2) λmax 332.5 nm; 1H NMR (CDCl3) δ 12.70 (br s, 1H), 8.33 (d, J=7.5 Hz, 2H), 7.87 (dd, J=5.9, 1.7 Hz, 1H), 7.72˜7.28 (m, 18H), 6.73 (d, J=16.3 Hz, 1H), 3.92˜3.76 (m, 2H), 3.67˜3.58 (dt J=11.5, 6.8 Hz, 1H), 2.63˜2.46 (m, 2H), 1.07 (s, 9H); 13C NMR (CDCl3) δ 151.88 (d J=19.2 Hz), 147.15, 139.01 (d, J=237.9 Hz), 136.78, 135.90, 135.49, 135.47, 133.00, 132.71, 130.01, 129.96, 129.91, 129.51, 129.18, 128.24, 127.76, 126.85 (d, J=34.4 Hz), 124.74, 105.60 (d, J=247.5 Hz), 67.01 (d, J=18.6), 66.43, 47.19, 41.64 (d, J=21.0 Hz), 26.68, 19.09; FABMS m/z 762 (M+H)+; Anal. Calcd for C38H37F2N3O3SSeSi: C, 59.99; H, 4.90; N 5.52; S, 4.21. Found: C, 59.97; H, 5.05; N, 5.44; S, 4.23.
