Reaction Steps
5-Iodo-2'-deoxyuridine (IDU) (3.54 g, 10 mmol) was coevaporated with dry pyridine (3×20 mL). The IDU was redissolved in dry pyridine (15mL) and 9-phenyl-9-chloroxanthen (3.82 g, 13 mmol) was added to the stirring solution in two equal portions over 0.5 h. After 1h, MeOH (5 mL) was added and the solution stirred for a further 0.5 h. The solvent was then removed under vacuum, and the residue recrystallized from a 1% Et2N/ethyl acetate solution giving 7 as colourless crystals (4.27 g, 70%), mp 200-2° C. 1H NMR (d6 -DMSO): δ2.20 (m, 2H, H2'), 2.99 (dd, 1H, H5', J-10.5, 4.2 Hz), 3.10 (dd, 1H, H5", J=10.5, 2.7 Hz), 3.85 (m, 1H, H4'), 4.15 (m, 1H, H3'), 5.29 (d, 1H, 3'OH, J=4.2 Hz), 6.08 (t, 1H, H1', J=7.0 Hz), 7.10-7.42 (m, 13H, Px CH), 8.08 (s, 1H, H6). 13C NMR (d6 -DMSO): δ40.4 (C2'), 63.8 (C5'), 69.9 (C5), 71.0 (C3'), 75.6 (Px C9), 85.2 (Cl'), 85.9 (C4'), 116.3, 116.4 (Px CH), 122.3, 122.4 (Px C8a and C9a), 123.8, 124.0, 125.8, 126.8, 128.2, 129.3, 129.69, 129.7, 129.73 (Px CH), 143.9 (C6), 148.4(Px Cl'), 150.0 (C2), 150.51, 150.58 (Px C4a and C10a), 160.6 (C4). FABMS m/z 633 (M+Na'). Anal. calcd for C28H23N2P6I: C, 55.1; H,3.81, N, 4.59. Found: C, 55.0; H, 3.81, N, 4.54.
