| Abstract
| - Nucleoside analogues bearing 2‘-C-α-(hydroxyalkyl) and 2‘-C-α-alkyl substitutes have numerousapplications in RNA chemistry and biology. In particular, they provide a strategy to probe the interactionbetween the 2‘-hydroxyl group of RNA and water. To incorporate these nucleoside analogues intooligonucleotides for studies of the group II intron (Gordon, P. M.; Fong, R.; Deb, S.; Li, N.-S.; Schwans,J. P.; Ye, J.-D.; Piccirilli, J. A. Chem. Biol.2004, 11, 237), we synthesized six new phosphoramiditederivatives of 2‘-deoxy-2‘-C-α-(hydroxyalkyl)cytidine (36: R = −(CH2)2OH; 38: R = −(CH2)3OH;40: R = −(CH2)4OH) and 2‘-deoxy-2‘-C-α-alkylcytidine (37: R = −CH2CH3; 39: R = −(CH2)2CH3;41: R = −(CH2)3CH3) from cytidine or uridine via 2‘-C-α-allylation, followed by alkene and alcoholtransformations. Phosphoramidites 36 and 37 were prepared from cytidine in overall yields of 14% (10steps) and 7% (11 steps), respectively. Phosphoramidites 38 and 39 were prepared from uridine in overallyields of 30% (10 steps) and 13% (11 steps), respectively. Phosphoramidites 40 and 41 were synthesizedfrom uridine in overall yields of 21% (13 steps) and 25% (14 steps), respectively.
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