S. Van Calenbergh et al.
OH:H2O) calculated for C17H19N3O7Na [M ϩ Na]ϩ 400.1120; 5.7 Hz, 1 H, C(1Ј)-H], 7.20Ϫ7.28 [m, 15 H, trityl], 7.82 [d, 4J ϭ
FULL PAPER
found 400.1198.
1.2 Hz, 1 H, C(6)-H] ppm. Exact mass (ESI-MS, iPrOH:H2O) cal-
culated for C29H26N5O4 [M ϩ H]ϩ 508.1984; found 508.1982.
1-(3-Azido-3-deoxy-β-D-ribofuranosyl)thymine (3a): A mixture of
1-(3-Azido-3-deoxy-5-O-trityl-β-D-arabinofuranosyl)thymine (5): A
thymine (838 mg, 6.7 mmol) in hexamethyldisilazane (120 mL),
chlorotrimethylsilane (0.85 mL), and dry pyridine (12 mL) was re-
fluxed overnight. After evaporation in vacuo, 2 (2.1 g, 5.5 mmol)
in dry 1,2-dichloroethane (50 mL) and trimethylsilyl trifluorome-
thanesulfonate (1.2 mL, 6.7 mmol) were added to the residue. After
5 h, CH2Cl2 (50 mL) and cooled 7% NaHCO3 solution (100 mL)
were added to the reaction mixture. The organic layer was sepa-
rated, washed twice with H2O (100 mL), dried with MgSO4, fil-
tered, and the solvents evaporated to dryness. The residue was dis-
solved in 0.15 NaOCH3 in CH3OH (100 mL), stirred for 1 h, and
neutralised with a H2O/CH3COOH (9:1) solution. The mixture was
evaporated in vacuo, purified by column chromatography (CH2Cl2/
MeOH, 95:5) and crystallised from CH3OH to yield 1.52 g (80%)
mixture of 4 (1.91 g, 3.76 mmol), 1 NaOH (10 mL), and 50 %
EtOH (100 mL) was stirred at room temperature for 4 hours. The
solution was neutralised with HOAc:EtOH (1:1, v/v) to pH ഠ 7.
The resulting white solid was collected by filtration and washed
with water. The solid was then dissolved in CH2Cl2, extracted with
water, dried with MgSO4, filtered, and evaporated to dryness to
produce 1.74 g (88.1 %) of 5 as a white solid. 1H NMR (300 MHz,
4
[D6]DMSO): δ ϭ 1.59 [d, J ϭ 0.6 Hz, 3 H, C(5)-CH3], 3.28 [dd,
2
3J ϭ 4.1 Hz and J5a’,5b’ ϭ Ϫ11.1 Hz, 2 H, C(5Ј)-Ha,b], 3.80 [app
3
3
quinted, 3J ϭ 4.1 Hz and J ϭ 8.2 Hz, 1 H, C(4Ј)-H], 4.15 [t, J ϭ
7.5 Hz, 1 H, C(3Ј)-H], 4.34 [m, 1 H, C(2Ј)-H], 6.07 [d, 3J ϭ 6.2 Hz,
1 H, C(1Ј)-H], 6.10 [d, 3J ϭ 5.6 Hz, 1 H, C(2Ј)-OH], 7.24Ϫ7.40 [m,
15 H, trityl], 7.38 [d, 4J ϭ 0.6 Hz, 1 H, C(6)-H], 11.34 [s, 1 H, N(3)-
H] ppm. Exact mass (ESI-MS, iPrOH:H2O) calculated for
C29H27N5O5Na [M ϩ Na]ϩ 548.1910; found 548.1906.
1
of the title compound 3a. H NMR (300 MHz, [D6]DMSO): δ ϭ
1.77 [d, 4J ϭ 1.2 Hz, 3 H, C(5)-CH3], 3.54 [dd, 3J ϭ 3.2 Hz and
2J5a’,5b’ ϭ Ϫ12.3 Hz, 1 H, C(5Ј)-Hb], 3.63 [dd, 3J ϭ 3.0 Hz, 1 H,
C(5Ј)-Ha], 3.84 [q, 3J ϭ 3.3 Hz and 3J ϭ 7.8 Hz, 1 H, C(4Ј)-H],
1-(3-Azido-3-deoxy-β-D-arabinofuranosyl)thymine (6a): A suspen-
3
3
4.06 [app t, J ϭ 5.1 Hz, 1 H, C(3Ј)-H], 4.40 [t, J ϭ 5.7 Hz, 1 H,
C(2Ј)-H], 5.29 [br. s, 1 H, C(5Ј)-OH], 5.74 [d, 3J ϭ 5.7 Hz, 1 H,
C(1Ј)-H], 6.13 [br. s, 1 H, C(2Ј)-OH], 7.69 [d, 4j ϭ 1.2 Hz, 1 H,
C(6)-H], 11.35 [br. s, 1 H, N(3)-H] ppm. 13C NMR (75 MHz,
[D6]DMSO): δ ϭ 12.85, 61.50, 61.81, 74.37, 82.44, 88.27, 110.16,
136.77, 151.41, 164.34 ppm. Exact mass (ESI-MS, iPrOH:H2O)
sion of compound 5 (0.5 g, 0.95 mmol) in 80% HOAc (10 mL) was
heated at 90 °C with stirring for 25 min. The solution was evapo-
rated in vacuo to give a residue that was chromatographed on a
silica gel column (CH2Cl2/MeOH, 95:5) to afford 0.2 g (78.6 %) of
1
4
6a. H NMR (300 MHz, [D6]DMSO): δ ϭ 1.74 [s, J ϭ 1.2 Hz, 3
3
H, C(5)-CH3], 3.62 [m, 3 H, C(4Ј)-H and C(5Ј)-Ha,b], 4.00 [t, J ϭ
calculated for C10H13N5O5Na [M
306.0798.
ϩ
Na]ϩ 306.0814; found
3
7.5 Hz, 1 H, C(3Ј)-H], 4.32 [t, J ϭ 6.6 Hz, 1 H, C(2Ј)-H], 5.29 [br.
s, 1 H, C(5Ј)-OH], 5.99 [d, 3J ϭ 6.2 Hz, 1 H, C(1Ј)-H], 6.07 [d,
3J ϭ 0.6 Hz, 1 H, C(2Ј)-OH], 7.58 [d, J ϭ 1.2 Hz, 1 H, C(6)-H],
4
O-2,2Ј-Anhydro-1-(3-azido-3-deoxy-5-O-trityl-β-D-arabinofuran-
11.27 [s, 1 H, N(3)-H] ppm. 13C NMR (75 MHz, [D6]DMSO): δ ϭ
12.84, 60.20, 64.84, 74.80, 80.26, 83.78, 108.70, 138.29, 151.14,
164.503 ppm. Exact mass (ESI-MS, iPrOH:H2O) calculated for
C10H13N5O5Na [M ϩ Na]ϩ 306.0814; found 306.0810.
osyl)hymine (4): (1.43 g, 5.1 mmol) of 3a and trityl chloride (1.55 g,
5.6 mmol) were dissolved in dry pyridine (15 mL). The reaction
mixture was heated at 65 °C for 7 hours, stirred overnight at room
temperature and the solvents evaporated to dryness. The residue
was dissolved in CH2Cl2 (150 mL) and washed subsequently with
7 % NaHCO3 solution (150 mL) and water (150 mL). The organic
layer was dried with MgSO4, filtered, and the solvents evaporated
to dryness. The residue was chromatographed on a silica gel col-
umn prepared in CH2Cl2/MeOH (99:1) and eluted with CH2Cl2/
MeOH (97:3) to give 2.46 g (92.7 %) of 1-(3-azido-3-deoxy-5-O-
1-(3-Azido-2-chloro-2,3-dideoxy-β-D-ribofuranosyl)thymine
(7a):
(310 mg, 0.61 mmol) of 4 was transferred into a sealable glass vial
and 4 HCl in dioxane (20 mL) was added. The vial was firmly
sealed and temperature was raised to 75Ϫ80 °C for 24 hours. After
cooling to room temperature the reaction mixture was evaporated
in vacuo and purified on a silica gel column CH2Cl2/MeOH (98:2)
to give 170 mg (92 %) of 7a. 1H NMR (300 MHz, [D6]DMSO):
trityl-β--ribofuranosyl)thymine:
1H
NMR
(300 MHz,
4
[D6]DMSO): δ ϭ 1.42 [d, J ϭ 0.9 Hz, 3 H, C(5)-CH3], 3.19 [dd,
4
3
δ ϭ 1.75 [d, J ϭ 1.2 Hz, 3 H, C(5)-CH3], 3.61 [ddd, J ϭ 3.0 Hz
2
3J ϭ 2.9 Hz and J5a’,5b’ ϭ Ϫ11.0 Hz, 1 H, C(5Ј)-Hb], 3.29 [dd,
and 3J ϭ 5.0 Hz and J5a’,5b’ ϭ Ϫ12.6 Hz, 1 H, C(5Ј)-Hb], 3.75
2
3J ϭ 3.8 Hz, 1 H, C(5Ј)-Ha], 3.97 [m, 1 H, C(4Ј)-H], 4.30 [q, J ϭ
3
[ddd, 3J ϭ 3.1 Hz and 3J ϭ 5.3 Hz, 1 H, C(5Ј)-Ha], 3.99 [app
3
3
5.4 Hz and J ϭ 10.8 Hz, 1 H, C(3Ј)-H], 4.57 [q, J ϭ 5.0 Hz and
quinted, 3J ϭ 2.9 Hz and 3J ϭ 3.13 Hz and 3J ϭ 6.0 Hz, 1 H,
3J ϭ 10.1 Hz, 1 H, C(2Ј)-H], 5.76 [d, J ϭ 5.4 Hz, 1 H, C(1Ј)-H],
3
3
3
C(4Ј)-H], 4.57 [t, J ϭ 5.7 Hz, 1 H, C(3Ј)-H], 4.92 [t, J ϭ 5.1 Hz,
1 H, C(2Ј)-H], 5.47 [t, J ϭ 4.7 Hz, 1 H, C(5Ј)-OH], 5.93 [d, J ϭ
4.7 Hz, 1 H, C(1Ј)-H], 7.80 [d, J ϭ 1.2 Hz, 1 H, C(6)-H], 11.46 [s,
3
6.24 [d, J ϭ 4.8 Hz, 1 H, C(2Ј)-OH], 7.21Ϫ7.40 [m, 15 H, trityl],
3
3
7.46 [d, 4J ϭ 1.2 Hz, 1 H, C(6)-H], 11.40 [s, 1 H, N(3)-H] ppm.
Exact mass (ESI-MS, iPrOH/H2O) calculated for C29H27N5O5Na
[M ϩ Na]ϩ 548.1910; found 548.1910. Trifluoromethanesulfonyl
chloride (1.0 mL, 9.36 mmol) was added to a cooled solution of 1-
4
1 H, N(3)-H] ppm. 13C NMR (75 MHz, [D6]DMSO): δ ϭ 12.92,
60.37, 61.10, 61.90, 83.12, 89.02, 110.23, 135.89, 151.17,
164.29 ppm. Exact mass (ESI-MS, iPrOH:H2O) calculated for
C10H13Cl1N5O4 [M ϩ H]ϩ 302.0655; found 302.0658.
(3-azido-3-deoxy-5-O-trityl-β--ribofuranosyl)thymine
(2.46 g,
4.68 mmol) and DMAP (2.30 g, 18.7 mmol) in dry CH2Cl2
(50 mL). After 2 hours the reaction was quenched with water
(15 mL) and extracted. The organic layer was washed with a 7 %
NaHCO3 solution, dried with MgSO4, filtered, and the solvents
evaporated to dryness to give a white semi-solid that was purified
1-(3-Azido-2,3-dideoxy-2-fluoro-β-D-ribofuranosyl)thymine (8a): To
a solution of 5 (1.59 g, 3.0 mmol) in toluene (30 mL) and pyridine
(3 mL), DAST (1.5 mL, 11.3 mmol) was added and stirred at room
temperature for 2 h before heating the reaction mixture to 50 °C.
on a silica gel column (CH2Cl2/MeOH, 97/3) to give 1.91 g (81 %) After 5 hours EtOAc (170 mL) was added and the organic layer
1
4
of 4. H NMR (300 MHz, [D6]DMSO): δ ϭ 1.79 [d, J ϭ 0.9 Hz,
washed successively with 7 % NaHCO3 (200 mL) and H2O
3
2
3 H, C(5)-CH3], 2.77 [dd, J ϭ 7.6 Hz and J5a’,5b’ ϭ Ϫ10.6 Hz, 1 (200 mL), dried with MgSO4, filtered, and concentrated in vacuo.
3
H, C(5Ј)-Hb], 3.04 [dd, J ϭ 4.1 Hz, 1 H, C(5Ј)-Ha], 4.38 [m, 1 H, The residue was purified on a silica gel column prepared in CHCl3
C(4Ј)-H], 4.60 [dd, 3J ϭ 1.8 Hz and 3J ϭ 3.2 Hz, 1 H, C(3Ј)-H],
and eluted with CHCl3/MeOH, 99:1 to give 1.45 g (90 %) of 1-(3-
5.43 [dd, 3J ϭ 1.6 Hz and 3J ϭ 5.7 Hz, 1 H, C(2Ј)-H], 6.31 [d, 3J ϭ azido-2,3-dideoxy-2-fluoro-5-O-trityl-β--ribofuranosyl)thymine:
2916
2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2003, 2911Ϫ2918