199792-82-0Relevant articles and documents
Nucleotides. Part LXV. Synthesis of 2'-Deoxyribonucleoside 5'-Phosphoramidites: New Building Blocks for the Inverse (5'-3')-Oligonucleotide Approach
Wagner, Thomas,Pfleiderer, Wolfgang
, p. 2023 - 2035 (2007/10/03)
The syntheses of the 3'-O-(4,4'-dimethoxytrityl)-protected 5'-phosphoramidites 25-28 and 5'-(hydrogen succinates) 29-32, which can be used as monomeric building blocks for the inverse (5'-3')-oligodeoxyribonucleotide synthesis are described (Scheme). These activated nucleosides and nucleotides were obtained by two slightly different four-step syntheses starting with the base-protected nucleosides 13-20. For the protection of the aglycon residues, the well-established 2-(4-nitrophenyl)ethyl (npe) and [2-(4-nitrophenyl)ethoxy]carbonyl (npeoc) groups were used. The assembly of the oligonucleotides required a slightly increased coupling time of 3 min in application of the common protocol (see Table 1). The use of pyridinium hydrochloride as an activator (instead of 1H-tetrazole) resulted in an extremely shorter activation time of 30 seconds. We established the efficiency of this inverse strategy by the synthesis of the oligonucleotide 3'-conjugates 33 and 34 which carry lipophilic caps derived from cholesterol and vitamin E, respectively, as well as by the formation of (3'-3')- and (5'-5')-internucleotide linkages (see Table 2).
