(2H, m, H-2ꢀ), 1.80 (1H, br s, CH3), 1.75 (1H, br s, CH3), 0.87
(9H, s, SiC(CH3)3), 0.09 (6H, s, Si(CH3)2). dC (75 MHz, DMSO-d6,
Me4Si) 164.3, 163.6 (C-4), 151.1, 150.4 (C-2), 142.3, 136.1 (C-6),
109.4, 107.7 (C-5), 87.1 (C-4ꢀ), 83.9 (C-1ꢀ), 73.2 (C-3ꢀ), 67.2 (C-5ꢀ),
50.7 (C-6ꢀ), 40.1 (C-2ꢀ), 25.6 (C(CH3)3), 17.6 (C(CH3)3), 12.3, 11.9
(CH3), −4.8, −5.0 (Si(CH3)2). HiRes MALDI FT-MS m/z (M +
Na) found/calc. 517.2082/517.2089.
m, H-2ꢀ, CH3), 0.74 (9H, s, SiC(CH3)3), −0.12 (3H, s, Si(CH3),
−0.23 (3H, s, Si(CH3). dC (75 MHz, CDCl3, Me4Si) 164.0, 163.9
(C-4), 152.2, 152.1 150.5 (C-2, Ph), 146.9, 141.2, 135.6, 131.2,
130.7, 130.5, 130.4, 128.1, 127.6, 123.8, 123.1, 122.6, 117.7, 117.3
(C-6, Ph), 111.3, 110.6 (C-5), 86.9, 85.1, 78.5, 73.5, 70.3 (C-1ꢀ,
C-3ꢀ, C-4ꢀ, C-5ꢀ, CPh3), 49.3 (C-6ꢀ), 41.2 (C-2ꢀ), 25.7 (C(CH3)3),
17.8 (C(CH3)3), 12.9, 12.4 (CH3), −4.5, −4.8 (Si(CH3)2). HiRes
MALDI FT-MS m/z (M + Na) found/calc. 773.2946/773.2977.
Preparation of 5ꢀ(S)-C-(thymin-1-ylmethyl)-5ꢀ-O-(4,4ꢀ-
dimethoxytrityl)thymidine (8)
Preparation of 5ꢀ(S)-C-(thymin-1-ylmethyl)-5ꢀ-O-pixylthymidine
(11)
Compound 6 (100 mg, 0.202 mmol) was dissolved in CH3CN
(5 mL) and pyridine (5 mL). The mixture was stirred at room
temperature and DMTCl (0.25 g, 0.74 mmol) was added. The
mixture was stirred for 24 h and another portion of DMTCl (0.47
g) was added. After another 24 h, DMTCl (0.53 g) together with
another CH3CN (5 mL) and pyridine (5 mL) was added and after
stirring for another 48 h, another portion of DMTCl (0.96 g).
After stirring for one week in total, the mixture was concentrated
under reduced pressure, and the residue was purified by column
chromatography to give the crude product 7 (101 mg). This was
dissolved in THF (1 mL) and a 1 M solution of TBAF in THF
(0.1 mL) was added. The reaction mixture was stirred for 5 h and
directly purified by column chromatography (0.2% pyridine and
50% diethyl ether in petroleum ether). The product was dissolved
in CH2Cl2 and precipitated in n-hexane to give the product (41 mg,
41%) as a white compound. dH (300 MHz, CDCl3, Me4Si) 8.40 (1H,
br s, NH), 8.34 (1H, br s, NH), 7.65 (1H, s, H-6), 7.45–7.15 (9H,
m, Ph), 6.88–6.81 (4H, m, Ph), 6.74 (1H, s, H-6), 6.27 (1H, t, J
6.9 Hz, H-1ꢀ), 4.30 (1H, m, H-3ꢀ), 4.02 (1H, m, H-5ꢀ), 3.85–3.53
(9H, m, H-4ꢀ, H-6ꢀ, OCH3), 2.33–2.23 (3H, m, H-2ꢀ, OH), 1.85
(1H, s, CH3), 1.79 (1H, s, CH3).
Compound 10 (70 mg, 0.093 mmol) was dissolved in THF (1 mL)
and a 1 M solution of TBAF in THF (0.1 mL) was added.
The mixture was stirred for 4 h and concentrated under reduced
pressure. The residue was purified by column chromatography
(0.5% Et3N in EtOAc) to give the product (32.2 mg, 54%). Rf
0.16 (EtOAc). dH (300 MHz, CDCl3, Me4Si) 9.04 (2H, br s, NH),
7.49–7.27 (10H, m, Ph, H-6), 7.10–6.99 (4H, m, Ph), 6.68 (1H, d,
J 0.9 Hz, H-6), 6.09 (1H, dd, J 6.3, 7.2 Hz, H-1ꢀ), 3.79 (1H, m),
3.52 (2H, br s), 3.34–3.18 (2H, m), (H-3ꢀ, H-4ꢀ, H-5ꢀ, H-6ꢀ), 2.14–
1.90 (5H, m, H-2ꢀ, CH3), 1.80 (3H, s, CH3). dC (75 MHz, CDCl3,
Me4Si) 164.3, 163.8 (C-4), 152.4, 152.2, 151.3, 150.5 (C-2, Ph),
146.6, 141.2, 131.2, 135.5, 130.8, 130.5, 130.4, 128.1, 127.7, 127.6,
123.9, 123.7, 123.1, 122.8, 117.7, 117.2 (C-6, Ph), 111.4, 110.6 (C-
5), 85.2, 83.9, 78.1, 70.8, 69.5 (C-1ꢀ, C-3ꢀ, C-4ꢀ, C-5ꢀ, CPh3), 49.4
(C-6ꢀ), 39.8 (C-2ꢀ), 13.0, 12.4 (CH3).
Preparation of 5ꢀ(S)-C-(thymin-1-ylmethyl)-5ꢀ-O-pixyl-3ꢀ-O-(P-b-
cyanoethoxy-N,N-diisopropylaminophosphinyl)thymidine (12)
Compound 11 (32 mg, 0.051 mmol) was dissolved in CH2Cl2
(3 mL), DIPEA (0.04 ml, 0.23 mmol) and CHCl3 (3 mL). The solu-
tion was stirred at room temperature and N,N-diisopropylamino-
b-cyanoethylphosphinochloridite (0.03 mL, 0.13 mmol) was
added. The reaction mixture was stirred for 3 h and concentrated
under reduced pressure. The residue was purified by column
chromatography (1% Et3N in EtOAc) as an oil. This was dissolved
in CH2Cl2 (0.2 mL) precipitated in n-hexane (1.5 mL), cooled
over night at −20 ◦C and centrifuged to give the product (27 mg,
64%) as a white solid. Rf 0.40 (EtOAc). dP (121.5 MHz, CDCl3)
151.98, 151.14. HiRes MALDI FT-MS m/z (M + Na) found/calc.
860.3257/860.3269.
Preparation of 5ꢀ(S)-C-(thymin-1-ylmethyl)-5ꢀ-O-(4,4ꢀ-dimethoxy-
trityl)-3ꢀ-O-(P-b-cyanoethoxy-N,N-diisopropylaminophosphinyl)-
thymidine (9)
Compound
8 was dissolved in CH2Cl2 (1.0 mL) and
DIPEA (0.1 mL). N,N-Diisopropylamino-b-cyanoethylphos-
phinochloridite (0.03 mL, 0.14 mmol) was added and the mixture
was stirred for 1.5 h and directly purified by column chromatogra-
phy (0.25% Et3N in EtOAc). The residue was dissolved in CH2Cl2
and precipitated in n-hexane to give the product (21.9 mg, 58%).
dP (121.5 MHz, CDCl3) 151.19, 150.28. HiRes MALDI FT-MS
m/z (M + Na) found/calc. 905.3609/905.9266.
Preparation of 5ꢀ(S)-C-(thymin-1-ylmethyl)-3ꢀ,5ꢀ-O-(1,1,3,
3-tetraisopropylsiloxan-1,3-diyl)thymidine (13)
Preparation of 5ꢀ(S)-C-(thymin-1-ylmethyl)-5ꢀ-O-pixyl-3ꢀ-O-
(tert-butyldimethylsilyl)thymidine (10)
Compound 8 (15 mg, 0.022 mmol) was dissolved in CDCl3
(0.5 mL) and added 2 drops of DCA. The mixture was stirred
for 2 min. and then added pyridine (1 mL) followed by an excess
of TIPDSCl (0.2 mL, 0.7 mmol). The mixture was stirred for 48 h,
added EtOH (0.1 mL) and concentrated under reduced pressure.
The residue was purified by column chromatography (25% EtOAc
in petrol ether and then 5% CH3OH in CH2Cl2) to give the product
(5.1 mg, 39%) as a white foam. dH (300 MHz, CDCl3, Me4Si) 8.60
(1H, s, NH), 8.48 (1H, s, NH), 7.31 (1H, d, J 0.9 Hz, H-6), 7.09
(1H, d, J 0.9 Hz, H-6), 6.17 (1H, dd, J 1.5 Hz, 7.8 Hz, H-1ꢀ),
4.52–4.43 (2H, m, H-3ꢀ, H-5ꢀ), 3.99–3.84 (2H, m, H-6ꢀ), 3.63 (1H,
dd, J 2.7 Hz, 8.4 Hz, H-4ꢀ), 2.51 (1H, m, H-2ꢀ), 2.23 (1H, m,
H-2ꢀꢀ), 1.94 (3H, d, J 0.9 Hz, CH3), 1.92 (3H, d, J 0.9 Hz, CH3),
Compound 6 (60 mg, 0.12 mmol) was dissolved in anhydrous
pyridine (1.5 mL) and pixyl chloride (121 mg, 0.41 mmol)
was added. The mixture was stirred for 12 h and concentrated
under reduced pressure. The residue was purified by column
chromatography (1% Et3N in EtOAc) to give the product (72 mg,
79%) as a white compound. Rf 0.23 (EtOAc). dH (300 MHz, CDCl3,
Me4Si) 9.14 (1H, m, NH), 8.60 (1H, m, NH), 7.76 (1H, d, J 1.2 Hz,
H-6), 7.45–7.26 (9H, m, Ph), 7.11–6.97 (4H, m, Ph), 6.75 (1H, d,
J 0.9 Hz, H-6), 6.25 (1H, dd, J 4.8 Hz, 9.3 Hz, H-1ꢀ), 3.77 (1H,
m, H-5ꢀ), 3.53 (1H, d, J 4.8 Hz, H-3ꢀ), 3.47 (1H, br s, H-4ꢀ), 3.33–
3.19 (2H, m, H-6ꢀ), 2.05–2.00 (4H, m, H-2ꢀ, CH3), 1.88–1.79 (4H,
1592 | Org. Biomol. Chem., 2007, 5, 1586–1594
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The Royal Society of Chemistry 2007
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