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1 2009

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Perspektywy stosowania metody blokowej do syntezy modyfikowanych oligonukleotydów w roztworze i na stałym podłożu

Bukowiecka-Matusiak M., Ziemecka I.

Wiadomości Chemiczne

2009

[Z] 63, 1-2

63-83

Studies on properties and function of nucleic acids constitute the most fascinating cognitive area in biology, chemistry and medicine. Dynamic development of the required techniques, primarily Nuclear Magnetic Resonance (NMR) [4], or crystallization techniques, allowed to obtain a detailed information about structural diversity of complicated biological compounds, for example peptides and nucleic acids. The replacement of one of the nonbonding oxygens of internucleotide bond by sulfur, selenium, methyl or other functionalized alkyl groups creates a stereogenic centre at the modified phosphorus atom [16]. This arises a question about availability of stereoregular, P-defined analogues of DNA and RNA. Short synthetic oligonucleotides are indispensable tools in biomolecular and structural studies [5, 6]. They also have potential as therapeutics [13, 14] for manipulation of genes expression in a sequence specific manner. The block synthesis assuming incorporation of P-chiral, diastereomerically pure dimeric building blocks is attractive, reliable and patent for automated approach to the synthesis of "chimeric oligonucleotides", both in solution and on solid support [23]. The attention of researches turned toward chimeric constructs of 16 containing, in successive internucleotide positions, phosphates and methanephosphonates. Reynolds et al. [34] found that for therapeutic applications, only chimeric oligonucleotides 16 with incorporated RP-dinucleoside methanephosphonates had acceptable binding affinity towards complementary template of DNA and RNA. Isosequential chimeric oligomers, constructed either from diastereomeric mixtures of dinucleoside methanephosphonates, or from those with SP-configuration, form less stable duplexes with the same complementary RNA templates. The preparation of the aforementioned chimeras utilized a "dimeric building blocks" approach [23]. The corresponding dinucleoside (3',5')-methanephosphonates 17 were separated into diastereomers by chromatographic methods. After removal of the 3'-O-protecting group, the required RP-isomers were activated at the 3'-O-position, and used as such for condensation via the phosphoramidite method [25]. Attempts towards their P-epimerization and recycling have failed. Such situation was notwithstanding the requirement of a cost-effective synthesis of new potential therapeutics. Therefore, Stec et al. [36-38], and efforts were undertaken in the design of a cost-effective synthesis of RP-dinucleoside (3',5')-methanephosphonates 17.