D- and L-Pyrimidine Arabino- and Ribonucleosides
233
added BSA (0.5 ml) and acetonitrile (0.5 ml). The open flask was placed
in a beaker containing neutral alumina, and the mixture was heated in a
microwave multi-mode reactor (170◦C, 160 W) for 30 minutes. The result-
ing black solid was suspended in CH2Cl2 and the insoluble material was
filtered off. The filtrate was evaporated and residue was purified by column
chromatography resulting in the desired nucleoside (Table 3).
1-(2ꢁ,3ꢁ, 5ꢁ-Tri-O-benzoyl-β-L-ribofuranosyl)-6-azauracil (6). Rf:
0.65
CH2Cl2/MeOH (9/1 v/v). H NMR(CDCl3) δ(ppm): 4.40 (m, 2H, H5ꢁ),
4.90 (m, 1H, H4ꢁ), 5.65 (m, 1H, H3ꢁ), 5.80 (m, 1H, H2ꢁ), 6.38 (d, 1H, H1ꢁβ,
J = 5.4Hz), 7.44 (s,1H, H5), 7.40–8.10 (m, 15H, Harom, Bz), 10.40 (s, 1H,
N-H). 13C NMR (CDCl3) δ(ppm), 63.66 (C5ꢁ), 71.38 (C4ꢁ), 75.09 (C3ꢁ),
79.99 (C2ꢁ), 88.00 (C1ꢁβ), 128.43–132.70 (Ph); 135.36 (C5), 149.26 (C4),
155.93 (C2), 165.05- 168 (PhCO). FAB-MS [M+H] + 558.
1
1-(2ꢁ,3ꢁ, 5ꢁ-Tri-O-benzoyl-α-L-arabinofuranosyl)-6-azauracil (8). Rf: 0.62
1
CH2Cl2/MeOH (9/1, v/v). H NMR (CDCl3) δ (ppm): 4.55(m, 2H, H5ꢁ),
4.85 (m, 1H, H4ꢁ), 5.86 (dd, 1H, H3ꢁ, J = 4.2 Hz, 3.3 Hz), 6.05 (m, 1H, H2ꢁ),
6.50 (d, 1H, H1ꢁα, J = 3.3 Hz), 7.40 -8.00 (m, 15H, Harom, Bz) 7.80 (s,1H,
H5), 10.30 (s, 1H, N-H). 13C NMR(CDCl3) δ(ppm): 63.78 (C5ꢁ), 77.49 (C3ꢁ),
80.73 (C2ꢁ), 83.28 (C4ꢁ), 90.19 (C1ꢁα), 128–133.9 (Ph), 147.8 (C5), 155.4
(C2), 155.9 (C4),165.2- 165.7 (PhCO). FAB-MS [M+H] + 558.
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