HETEROCYCLES, Vol. 65, No. 12, 2005
2997
2.87 (1H, br s, 5'-OH), 1.63 (3H, s, 2',3'-O-isopropylidene-CH3), 1.37 (3H, s, 2',3'-O-isopropylidene-CH3),
1.18-1.29 (3H, m, 4'-OCH2CH3). Anal. Calcd for C14H20N2O7: C, 51.21; H, 6.14; N, 8.53. Found: C,
51.05; H, 6.25; N, 8.32.
1
12: MS (EI) m/z: 313 (M+-CH3, 5%), 217 (S+, 9%), 112 (B+-1, 44%), 59(100%). H NMR (CDCl3) δ:
9.40 (1H, br s, N3-H), 7.49 (1H, d, J=8.1 Hz, 6-H), 6.34 (1H, d, J=1.5 Hz, 1'-H), 5.78 (1H, d, J=8.1 Hz,
5-H), 4.98 (1H, dd, J=6.3 and 1.5 Hz, 2'-H), 4.77 (1H, d, J=6.3 Hz, 3'-H), 3.83-3.95 (2H, m,
4'-OCH2CH3), 3.64-3.75 (1H, m, 5'-Ha), 3.45-3.56 (1H, m, 5'-Hb), 2.27 (1H, br s, 5'-OH), 1.58 (3H, s,
2',3'-O-isopropylidene-CH3), 1.36 (3H, s, 2',3'-O-isopropylidene-CH3), 1.18 (3H, t, J=6.8 Hz,
4'-OCH2CH3). HRMS (FAB+) m/z Calcd for C14H21N2O7 (M++1): 329.1348. Found: 329.1353.
5'-O-(4,4'-Dimethoxytrityl)-2',3'-O-isopropyliden-4'-methoxyuridine
(13)
and
1-[5-O-(4,4'-
dimethoxytrityl)-2,3-O-isopropylidene-4-methoxy-α-L-lyxofuranosyl]uracil (14)
To a stirred solution of a mixture of 9 and 10 (314 mg, 1.0 mmol; 9 : 10 = 9 : 8) in dry pyridine (5 mL)
was added DMTr-Cl(4,4'-dimethoxytrityl chloride) (508 mg, 1.5 mmol) at rt under argon atmosphere.
The reaction mixture was stirred for 9 h and the mixture was concentrated in vacuo and remaining
pyridine was removed as a toluene azeotrope. The residue was partitioned between CHCl3 and sat.
NaHCO3. The organic layer was washed with water and dried over MgSO4. The solvent was evaporated
in vacuo and the residue was subjected to silica gel column chromatography (CHCl3 : MeOH = 100 : 1) to
afford 13 (275 mg, 45%) as the first fraction (white foam) and 14 (243 mg, 39%) as the second fraction
(white foam).
13: IR (KBr) νmax/cm-1: 1693, 1508, 1458, 1380, 1249 and 1087. MS (EI) m/z: 616 (M+, 2%), 303
(DMTr+, 100%). 1H NMR (CDCl3) δ: 8.72 (1H, br s, N3-H), 7.63 (1H, d, J=8.1 Hz, 6-H), 7.23-7.36 (9H,
m, DMTr-H), 6.82-6.85 (4H, m, DMTr-H), 6.22 (1H, d, J=2.4 Hz, 1'-H), 5.34 (1H, d, J=8.1 Hz, 5-H),
5.10 (1H, d, J=6.8 Hz, 3'-H), 4.75 (1H, dd, J=6.8 and 2.4 Hz, 2'-H), 3.80 (6H, s, DMTr-OCH3), 3.56 (1H,
d, J=9.8 Hz, 5'-Ha), 3.36 (1H, d, J=9.8 Hz, 5'-Hb), 3.31 (3H, s, 4'-OCH3), 1.61 (3H, s,
2',3'-O-isopropylidene-CH3), 1.38 (3H, s, 2',3'-O-isopropylidene-CH3). 13C NMR (CDCl3) δ: 162.69 (4-C),
158.78 (DMTr-C), 149.83 (2-C), 144.04 (DMTr-C), 140.42 (6-C), 134.91 (DMTr-C), 130.21 (DMTr-C),
130.17 (DMTr-C), 128.20 (DMTr-C), 128.02 (DMTr-C), 127.25 (DMTr-C), 116.26 (DMTr-C), 113.31
(DMTr-C), 106.33 (2',3'-O-isopropylidene), 102.94 (5-C), 88.77 (1'-C), 87.36 (4'-C), 84.67 (2'-C), 80.85
(3'-C), 62.87 (5'-C), 55.27 (DMTr-OCH3), 50.62 (4'-OCH3), 25.99 (2',3'-O-isopropylidene-CH3), 25.88
(2',3'-O-isopropylidene-CH3). HRMS (EI) m/z Calcd for C34H36N2O9 (M+): 616.2421. Found: 616.2414.
14: IR (KBr) νmax/cm-1: 1690, 1508, 1458, 1380, 1250 and 1099. MS (EI) m/z: 616 (M+, 2%), 303
(DMTr+, 100%). 1H NMR (CDCl3) δ: 8.68 (1H, br s, N3-H), 7.56 (1H, d, J=7.8 Hz, 6-H), 7.20-7.45 (9H,
m, DMTr-H), 6.80-6.83 (4H, m, DMTr-H), 6.24 (1H, d, J=1.5 Hz, 1'-H), 5.70 (1H, d, J=7.8 Hz, 5-H),
4.98 (1H, dd, J=5.4 and 1.5 Hz, 2'-H), 4.88 (1H, d, J=5.4 Hz, 3'-H), 3.79 (6H, s, DMTr-OCH3), 3.56 (1H,