Helvetica Chimica Acta Vol. 86 (2003)
2317
11.9. 1H-NMR ((D6)DMSO): 12.1 (s, NH); 11.2 (br. s, OH); 10.5 (s, HÀN(6); 10.1; 8.75 (s, HÀC(2)); 8.71
(s, HÀC(8)); 8.54 (dd, HÀC(6)(flu)); 7.99 (dd, HÀC(4)(flu)); 7.45 (d, HÀC(3)(flu)); 6.89 6.52 (m, 6 arom. H
(xan); 6.33 (d, HÀC(1')); 6.05 (t, HÀC(2')); 5.64 (t, HÀC(3')); 4.44 (m, 2 HÀC(5')); 4.28 (m, HÀC(4')); 3.59
(s, MeO); 2.12, 2.04, 202 (3 s, 3 Ac).
10. N6-{{[4-(6-Hydroxy-3-oxo-3H-xanthen-9-yl)-3-(methoxycarbonyl)phenyl]amino}carbonyl}adenosine
(14). A soln. of 13 (0.6 g, 0.77 mmol), K2CO3 (0.2 g), and Bu4NBr (50mg) in MeOH (30ml) was stirred at
r.t. for 2.5 h, then diluted with H2O (100 ml), acidified with a few drops of AcOH, and concentrated to 20 ml.
The resulting precipitate was collected, then stirred in MeOH for 2 h, filtered again, and dried under high
vacuum: 0.38 g (73%) of 14. M.p. 208 2098. TLC (iPrOH/conc. NH3 soln./H2O 7:1 :2): Rf 0.57. UV (pH 9): 238
(4.72), 258 (sh., 4.48), 280(4.64), 316 (4.08), 348 (sh., 3.81), 460(sh., 4.40), 494 (4.91). 1H-NMR ((D6)DMSO):
12.1 (s, NH); 10 .4 (br. s, HÀN(6), OH); 8.70 (s, HÀC(2), HÀC(8)); 8.5 (dd, HÀC(6)(flu)); 8.00
(dd, HÀC(4)(flu)); 7.51 (d, HÀC(3)(flu)); 7.5 7.0( m, 6 arom.
H
(xan); 6.05 (d, HÀC(1')); 5.7 5.0
(m, HÀC(2'), HÀC(3', OH); 3.99 (m, HÀC(4')); 3.52 (m, 2 HÀC(5')). Anal. calc. for C32H26N6O10 ¥ H2O
(654.6): C 57.14, H 4.10, N 12.49; found: C 57.36, H 4.32, N 12.91.
11. 2',3',5'-Tri-O-acetyl-N4-(phenoxycarbonyl)cytidine (15). A mixture of 2',3',5'-tri-O-acetylcytidine
(0.74 g, 2 mmol) [29] and 1-(phenoxycarbonyl)-1H-tetrazole (2.5 g, 13 mmol) in dioxane (10ml) was stirred
at 408 for 30min. After evaporation, the residue was purified by FC (12 Â 2.5 cm; toluene (50ml), toluene/
acetone 9 :1 (200 ml), toluene/acetone 4 :2 (600 ml); 50-ml fractions). Fr. 13 16 gave 0.6 g (61%) of 15.
Colorless solid foam. TLC (toluene/acetone 1:1): Rf 0.5. UV (MeOH): 243 (4.28), 264 (3.89). 1H-NMR
((D6)DMSO): 11.4 (br. s, NH); 8.14 (d, HÀC(6)); 7.47 7.17 (m, Ph); 7.0 6 (d, HÀC(5)); 5.90( d, HÀC(1')); 5.49
(dd, HÀC(2')); 5.36 (t, HÀC(3')); 4.38 4.17 (m, HÀC(4'), 2 HÀC(5')); 2.07, 2.06 2.03 (3 s, 3 Ac). Anal. calc.
for C22H23N3O10 (489.4): C 53.99, H 4.74, N 8.59; found: C 54.08. H 4.71, N 9.02.
12. 2',3',5'-Tri-O-acetyl-N4-[(fluorescein-5-ylamino)carbonyl]cytidine (2',3',5'-Tri-O-acetyl-N4-{[(3',6'-di-
hydroxy-3-oxospiro[isobenzofuran-1(3H),9'-[9H]xanthen]-5-yl)amino]carbonyl}cytidine; 16). A mixture of 7
(0.52 g, 1.5 mmol) and 15 (1.2 g, 2.4 mmol) in pyridine (10ml) was heated to 70 8 for 3 h. Stirring was continued
overnight, the mixture evaporated and co-evaporated with toluene, and the residue dissolved in CH2Cl2/MeOH
and submitted to FC (13 Â 3.5 cm; CH2Cl2 (100 ml), CH2Cl2/MeOH 97:3 (200 ml), CH2Cl2/MeOH 95 :5
(100 ml), CH2Cl2/MeOH 93 :7 (200 ml), CH2Cl2/MeOH 9 :1 (300 ml; 50-ml fractions). Fr. 14 18 were
evaporated and co-evaporated with toluene and then the residue dried to give 1.1 g (97%) of crude material. A
sample (0.3 g) was heated in acetone (50 ml), the soln. filtered, and then Et2O (30ml) slowly added with
stirring. The yellow precipitate was collected and dried under high vacuum at 508: 0.26 g (85%) of pure 16. TLC
(CH2Cl2/MeOH 4 :1): Rf 0.63. UV (pH 9): 238 (4.73), 260 (sh., 4.40), 288 (4.89), 316 (4.14), 348 (sh., 3.88), 428
(sh., 3.70), 456 (sh., 4.38), 491 (4.91). 1H-NMR ((D6)DMSO): 11.6 (br. s, NH); 10.5 (s, NH); 10.1 (s, OH); 8.22
(d, HÀC(6)(flu)); 8.05 (d, HÀC(6)); 7.67 (m, HÀC(4)(flu)); 7.24 (m, HÀC(3)(flu), HÀC(5)); 6.67 6.48
(m, 6 arom. H (xan)); 5.91 (d, HÀC(1')); 5.50( dd, HÀC(2')); 5.37 (t, HÀC(3')); 4.37 4.19 (m, HÀC(4'),
2 HÀC(5')); 2.06, 2.04 (2 s, 3 Ac). Anal. calc. for C36H30N4O14 (742.7): C 58.22, H 4.07, N 7.54; found: C 57.59, H
4.25, N 7.46.
13. 2',3',5'-Tri-O-acetyl-N4-{{[4-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-3-(methoxycarbonyl)phenyl]amino}-
carbonyl}cytidine (17). A mixture of 9 (0.2 g, 0.55 mmol) and 15 (0.5 g, 1 mmol) in pyridine (10 ml) was
heated to 708 for 2 h. The soln. was evaporated and co-evaporated with toluene, the residue treated with warm
dioxane by ultrasound, collected, and then dissolved in dioxane/MeOH 1:1 (50ml). The soln. was filtered hot
and MeOH carefully removed until a precipitate formed. After standing overnight, the solid was collected and
dried: 0.26 g (63%) of 17. Yellow powder. M.p. 188 1908 (dec.). TLC (CH2Cl2/MeOH 9 :1): Rf 0.45. UV (Ho
À
1.54): 226 (4.76), 249 (4.59), 310(4.54), 376 (3.91), 439 (4.74). UV (pH 1): 223 (4.75), 248 (4.60), 297 (4.44), 360
(sh., 3.64), 439 (4.72). UV (pH 4): 216 (4.67), 232 (4.68), 256 (sh., 4.46), 275 (4.46), 292 (sh., 4.42), 372 (3.99),
458 (4.42), 474 (4.41). UV (pH 8): 216 (4.71), 238 (4.77), 259 (sh., 4.46), 288 (4.47), 318 (sh., 4.19), 346 (sh.,
3.85), 434 (sh., 3.81), 464 (sh., 4.46), 496 (4.93). UV (pH 13): 219 (4.63), 239 (4.76), 258 (sh., 4.45), 288 (4.45),
309 (4.55), 313 (sh., 4.45), 365 (sh., 3.89), 434 (sh., 3.81), 464 (sh., 4.50), 494 (4.95). pKa Values: 0.40, 2.79, 6.13,
11.33. 1H-NMR ((D6)DMSO): 11.6 (br. s, NH); 11.1 (s, OH); 10.5 (s, NH); 8.34 (m, HÀC(6)(flu)); 8.08
(d, HÀC(6)); 7.88 (m, HÀC(4)(flu)); 7.43 (m, HÀC(3)(flu)); 6.87 6.52 (m, HÀC(5), 6 arom. H (xan); 5.92
(d, HÀC(1')); 5.50( dd, HÀC(2')); 5.37 (t, HÀC(3')); 4.37 4.22 (m, HÀC(4', 2 HÀC(5')); 3.59 (s, MeO); 2.07,
2.05 (2 s, 3 Ac). Anal. calc. for C37H32N4O14 (756.7): C 58.73, H 4.26, N 7.40; found: C 58.59, H 4.24, N 6.96.
14. 3',5'-Di-O-acetyl-2'-deoxy-O6-[2-(4-nitrophenyl)ethyl]guanosine (18). A mixture of 3',5'-di-O-acetyl-2'-
deoxyguanosine [30] (0.702 g, 2 mmol), PPh3 (0.84 g, 3.2 mmol), and 2-(4-nitrophenyl)ethanol (0.501 g,
3 mmol) in dry dioxane (40ml) was stirred for 5 min. Then, diethyl azodicarboxylate (0.558 g, 3.2 mmol) was
added and stirred vigorously for 1 h at r.t. ( ! clear soln.). The soln. was evaporated and the residue treated