SOMMAIRE

J.MAR.CHIM.HETEROCYCL. Volume 1, N° 1 Décembre 2002
Prolabo) and TLC on silica gel 60, F254 (Merck) with detection by UV absorbance or
phosphomolybdic acid.
2. Preparation of nucleoside analogues 8 and 9.
To a cooled stirred solution of protected nucleoside (6,7) (0.5 g, 0.91 mmol) in ethanol (10 ml)
was slowly added a solution of sodium periodate (0.23 g, 1.09 mmol) in water (5 ml). The reaction
mixture was stirred at room temperature during 2 hours and then filtered to remove salts. The
solution was treated with AcOEt (15 ml), washed twice with a satured solution of NaCl (2 x 15 ml)
and dried over MgSO4. The solvent was removed by evaporation under reduced pressure to yield a
white powder of the dialdehyde derivative. The product, in solution in fresh distillated
tetrahydrofuran (5 ml), was added without purification to a yellow solution of
methyltriphenylphosphine bromide (1.3 g, 3.66 mmol) and potassium-tert-butoxide (0.41 g, 3.66
mmol) in toluene (50 ml) at 60°C under argon. After one hour, the mixture was cooled at room
temperature, washed twice by a satured solution of ammonium chloride (2 x 30 ml), dried over
MgSO4, reduced to yellow syrup and purified by column chromatography (silica gel) to afford 8
and 9.
2.1. 3-O-[1-(Thymin-1-yl)-prop-2-enyl]-4-O-trityl-but-1-en-3,4-diol (8).
The title compound was obtained as an oil (0.24 g., 50 %) following the aforementioned
procedure after chromatography with hexane:ethyl acetate (60:40) as the eluent. Rf 0.4
(hexane:ethyl acetate, 65:35); δH (CDCl3) 1.72 (3H, s, CH3 thymine), 2.97 (1H, dd, J 2.4, J 8.0, H-
4a), 3.27 (1H, dd, J 5.9, J 8.0, H-4b), 3.79 (1H, m, J 2.4, J 5.9, J 8.0, H-3), 5.22 (2H, m, H-1a,b or
H-3a,b-prop-2-enyl), 5.35 (1H, m, H-2 or H-2-prop-2-enyl), 5.53 (2H, m, H-1a,b or H-3a,b-prop-2enyl),
5.74 (1H, m, H-2 or H-2-prop-2-enyl), 6.20 (1H, m, H-1-prop-2-enyl), 7.13–7.35 (16 H, m,
aromatic H, H-6 thymine), 9.15 (1H, s, NH thymine); δC (CDCl3 ) 12.5 (CH3 thymine), 66.3 (C-4),
78.3, 80.0 (C-3, C-1-prop-2-enyl), 86.8 (Civ), 111.6 (C-5 thymine), 119.2, 120.7 (C-2, C-2-prop-2enyl),
127.1, 127.8, 128.6 (C aromatic), 133.0, 133.7 (C-1, C-3-prop-2-enyl), 136.2 (C-6 thymine),
143.9 (C aromatic), 151.2 ( C-2 thymine), 164.0 (C-4 thymine).
2.2. 3-O-[1-(Uvaril-1-yl)-prop-2-enyl]-4-O-dimethoxytrityl-but-1-en-3,4-diol (9).
The title compound was obtained as an oil (0.25 g., 50 %) following the aforementioned
procedure after chromatography with hexane:ethyl acetate (10:10) as the eluent. Rf 0.5
(hexane:ethyl acetate, 1:1); δH (CDCl3) 3.07 (1H, dd, J 3.1, J 10.4, H-4a), 3.36 (1H, dd, J 8.1, J
10.4, H-4b), 3.80 (6H, s, OCH3), 3.92 (1H, m, J 3.1, J 8.1, J 12.3, H-3), 5.38, 5.61, 5.78 (7H, 3m, H-
1a,b, H-2, H-2-prop-2-enyl, H-3a,b-prop-2-enyl, H-5 uracile), 6.29 (1H, m, H-1-prop-2-enyl), 6.84
(4H, m, aromatic H), 7.25–7.54 (11 H, m, aromatic H, H-6 uracile), 9.55 (1H, s, NH uracile); δC
(CDCl3 ) 55.6 (OCH3), 66.3 (C-4), 78.8, 80.7 (C-3, C-1-prop-2-enyl), 86.7 (Civ), 103.5 (C-5
uracile), 113.5 (C aromatic), 119.7, 121.2 (C-2, C-2-prop-2-enyl), 127.3, 128.2, 128.6, 130.4, 130.5
(C aromatic), 133.2, 133.9 (C-1, C-3-prop-2-enyl), 136.2, 136.3 (C-aromatic), 141.2 (C-6 uracile),
145.1 (C aromatic), 151.5 (C-2 uracile), 159.0 (C aromatic), 164.0 (C-4 uracile).
2.3. 3-O-[1-(Cytosin-1-yl)-prop-2-enyl]-4-O-dimethoxytrityl-but-1-en-3,4-diol (11).
A solution of 1,2,4-1-H-triazole (0.57 g, 9.66 mmol) and POCl3 (0.17 ml, 2.02 mmol) in
acetonitrile (6 ml) was cooled at 0°C. Et3N (1.1 ml, 9.24 mmol) was then added and the mixture was
stirred 30 minutes at room temperature. 0.5 g (0.92 mmol) of 9 in acetonitrile (3 ml) was added and
the heterogen mixture was stirred overnight at room temperature. After addition of Et3N (0.9 ml)
and H2O (0.4 ml), the homogen solution was stirred over 15 minutes, dissolved in dichloromethane
(15 ml), washed twice by a satured solution of Na2CO3 (2 x 15 ml), dried over MgSO4 and reduced
to yellow powder of 1,2,4-triazolyl derivative 10. This one, without purification, was dissolved in
9