- Reliable chemical synthesis of oligoribonucleotides (RNA) with 2′-O-[(triisopropylsilyl)oxy]methyl(2′-O-tom)-protected phosphoramidites
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A method for the introduction of the 2′-O-[(triisopropylsilyl)oxy]methyl (=tom) group into N-acetylated, 5′-O-dimethoxytritylated ribonucleosides is presented. The corresponding 2′-O-tom-protected phosphoramidite building blocks were obtained in pure form and were successfully employed for the routine synthesis of oligoribonucleotides on DNA synthesizers. Under DNA coupling conditions (2.5 min coupling time for a 1.5-μmol synthesis scale) and with 5-(benzylthio)-1H-tetrazole (BTT) as activator, 2′-O-tom-protected phosphoramidites exhibited average coupling yields >99.4%. The combination of N-acetyl and 2′-O-tom protecting groups allowed a reliable and complete two-step deprotection, first with MeNH2 in EtOH/H2O and then with Bu4NF in THF, without concomitant destruction of the product RNA sequences.
- Pitsch, Stefan,Weiss, Patrick A.,Jenny, Luzi,Stutz, Alfred,Wu, Xiaolin
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p. 3773 - 3795
(2007/10/03)
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- Fast and reliable automated synthesis of RNA and partially 2'-O- protected precursors ('caged RNA') based on two navel, orthogonal 2'-O- protecting groups. Preliminary communication
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Two sets of RNA phosphoramidites, carrying the (fluoride-labile) 2'-O- [(triisopropylsilyl)oxy]methyl (=tom) group and the (photolabile) [(R)-1-(2- nitrophenyl)ethoxy]methyl (= (R)-npeom) group, were prepared (see 1-4 and 5- 8, resp.). The two protecting groups were completely orthogonal to each other. Three ribozyme-substrate constructs, protected each by a (R)-npeom group, were synthesized; on photolysis, efficient cleavage of this remaining protecting group occurred (Scheme 3). It could be demonstrated that the presence of one (R)-npeom group within a RNA strand has only a minor influence on the pairing properties of corresponding duplexes.
- Pitsch, Stefan,Weiss, Patrick A.,Wu, Xiaolin,Ackermann, Damian,Honegger, Thomas
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p. 1753 - 1761
(2007/10/03)
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