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Zhu,Williams,and Scott
The solid was collected by filtration, washed with cooled water
(8 Â 25 mL), and dried under reduced pressure overnight. 3 was obtained
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as a white solid (4.16 g, 98%). H NMR (500 MHz, CDCl3) ꢀ8.68 (d,
J ¼ 6.96 Hz, 1H, 6-H), 8.62 (s, br, 1H, NH), 7.87 (d, J ¼ 6.70 Hz, 2H,
arom. H), 7.59 (t, J ¼ 7.40 Hz, 1H, arom. H), 7.51–7.45 (m, 3H, 2
arom. HþH-5), 5.79 (s, 1H, 10-H), 4.15 (ddd, J ¼ 8.32, 1.96, 1.32 Hz,
1H, 40-H), 4.11 (d, J ¼ 4.04 Hz, 1H, 20-H), 4.06 (dd, J ¼ 8.32, 4.04 Hz,
1H, 30-H), 4.03 (dd, J ¼ 11.75, 1.92 Hz, 1H, 50-H), 3.71 (dd, J ¼ 11.75,
1.36 Hz, 1H, 50-H), 0.20 (s, 9H), 0.19 (s, 9H), 0.10 (s, 9H); 13C NMR
(125 MHz, CDCl3) ꢀ166.8 (1C), 162.1 (1C), 154.7 (1C), 145.1 (1C),
133.2 (1C), 133.0 (1C), 128.9 (2C), 127.5 (2C), 95.6 (1C), 91.6 (1C),
82.6 (1C), 76.5 (1C), 68.1 (1C), 59.3 (1C), 0.27 (3C), 0.008 (3C), ꢁ0.73
(3C); HRMS [MþH]þ, Found: 564.2373, C25H42O6N3Si3 requires m/z
564.2381.
TMS protected adenosine intermediates. Adenosine (7.5 mmol,
suspended in 30 mL of pyridine) was first silylated and benzoylated
(Sch. 2), the reaction was then cooled to 0ꢀC. To this mixture was
added K2HPO4 (12 g) and ice-water (60 g). The mixture was then diluted
with 200 mL CH2Cl2 and washed with brine (40 mL). The organic phase
was dried over Na2SO4 and evaporated at reduced pressure. The residue
was subjected to flash chromatography on silica gel (Eluent:
EtOAc/Hexane ¼ 1:8 to 1:2) to provide three TMS protected intermedi-
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ates 4, 5 and 6 as white solids. O2 ,O3 ,O5 -tris-trimethylsilyl-N6,N6-diben-
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zoyladenosine (4) (0.99 g, 19%). H NMR (500 MHz, CDCl3) ꢀ 8.63 (s,
1H), 8.41 (s, 1H), 7.83 (d, J ¼ 7.37 Hz, 4H, arom. H), 7.45 (t, J ¼ 7.43 Hz,
2H, arom. H), 7.31 (dd, J ¼ 7.43, 7.37 Hz, 4H, arom. H), 6.09 (d,
J ¼ 4.80 Hz, 1H, 10-H), 4.63 (t, J ¼ 4.58 Hz, 1H, 20-H), 4.26 (t,
J ¼ 4.20 Hz, 1H, 30-H), 4.12 (m, 1H, 40-H), 3.90 (dd, J ¼ 11.46, 3.50 Hz,
1H, 50-H), 3.72 (dd, J ¼ 11.46, 2.72 Hz, 1H, 50-H), 0.14 (s, 18H), ꢁ0.054
(s, 9H); 13C NMR (125 MHz, CDCl3) ꢀ 172.2 (2C), 152.9 (1C), 152.1
(1C), 151.7 (1C), 143.8 (1C), 134.2 (2C), 132.8 (2C), 129.4 (4C), 128.6
(4C), 128.1 (1C), 88.6 (1C), 85.3 (1C), 75.8 (1C), 71.6 (1C), 61.4 (1C),
0.235 (3C), ꢁ0.092 (3C), ꢁ0.653 (3C); HRMS [MþH]þ, Found: 692.2742,
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C33H46O6N5Si3 requires m/z 692.2756. O2 ,O3 ,O5 -tris-trimethylsilyl-N6-
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benzoyladenosine (5) (1.32 g, 30%). H NMR (500 MHz, CDCl3) ꢀ 9.02
(s, 1H, NH), 8.79 (s, 1H), 8.43 (s, 1H), 8.00 (dd, J ¼ 7.19, 1.34 Hz, 2H,
arom. H), 7.58 (td, J ¼ 7.39, 1.34 Hz, 1H, arom. H), 7.49 (dd, J ¼ 7.39,
7.19 Hz, 2H, arom. H), 6.10 (d, J ¼ 4.31 Hz, 1H, 10-H), 4.62 (t,
J ¼ 4.35 Hz, 1H, 20-H), 4.28 (t, J ¼ 4.48 Hz, 1H, 30-H), 4.16–4.13 (m,
1H, 40-H), 3.94 (dd, J ¼ 11.44, 3.31 Hz, 1H, 50-H), 3.73 (dd, J ¼ 11.44,
2.56 Hz, 1H, 50-H), 0.17 (s, 9H), 0.14 (s, 9H), ꢁ0.0012 (s, 9H); 13C NMR
(125 MHz, CDCl3) ꢀ 164.5 (1C), 152.7 (1C), 151.6 (1C), 149.3 (1C),