Oligo- and Poly-nucleotides

Nucleotides in aqueous solution can be alkylated at the phosphate (and in some cases the nucleoside also) by the action of l-oxidopyridin-2-yldiazo-methane (33). - The protecting group may be removed from the phosphate with snake venom phosphodiesterase, or generally by acetic anhydride treatment, followed by ammonia. Phosphoramidates have been described previously as phosphate-protecting groups, and if 2-naphthylamine is used as its anilidate for this purpose, organic solvent extraction (as above) is possible. A variation on this theme is to use dianilidophosphochloridate (34) as a 

Ohtsuka, A. Honda, H. Shigyo, S. Morioka, T. Sugiyama, and M. Ikehara, Nucleic Acid Res., 1974, 1, 223. 

Arylsulphonyl 1,2,4-triazolides (35), prepared from the appropriate aryl-sulphonyl chloride and IjH-1,2,4-triazole, can be used to activate phospho-monoesters or -diesters for condensation reactions in polynucleotide synthesis. Yields for condensations involving guanosine residues are better than those obtained using aryl sulphonyl chlorides. 

Nucleoside O-phosphorothioates react with acrylonitrile at pH 8—9 to give 5-cyanoethyl derivatives, which may then be condensed with other nucleosides. Treatment with ammonia eliminates the cyanoethyl group, giving a dinucleoside 0,0-phosphorothioate. A number of these compounds, including Tp Tp T, have been prepared.  

Oligo- and Poly-nucleotides.—The stepwise enzymatic synthesis of internucleotide bonds has been reviewed. A number of polynucleotides containing modified bases have been synthesised in the past year from nucleoside triphosphates with the aid of a polymerase enzyme, and the enzymatic synthesis of oligodeoxyribonucleotides using terminal deoxynucleotidyl transferase has been studied. Primer-independent polynucleotide phosphorylase from Micrococcus luteus has been attached to cellulose after the latter has been activated with cyanogen bromide. The preparation of insolubilized enzyme has enabled large quantities of synthetic polynucleotides to be made. The soluble enzyme has been used to prepare various modified polycytidylic acids.  

Setondji, R. Remy, J. P. Ebel, and G. Dirheimer, Biochim. Biophys. Acta, 1971, 232, 585. 

As mentioned in last year s Report, aromatic phosphoramidates have been used to protect 5 -phosphoryl groups in the stepwise synthesis of oligodeoxyribonucleotides. The appropriate monomer units are coupled with DCC and the phosphoramidate protecting group is removed when required with isoamyl nitrite. A rapid and general preparative method for oligonucleotides has been developed based on phosphoramidates of the highly lipophilic 4-aminophenyltriphenylmethane (25). Purification of 

The amino-acid acceptor ends of a number of tRNAs terminate with 

An alternative approach to the synthesis of internucleotide bonds is to use an insoluble condensing agent, such as poly(3,5-diethylstyrene)sulphonyl chloride.116 

If a deoxyribonucleoside 5 -monophosphate is first esterified with a bulky apolar group, and then used as the 5 -terminus for synthesis of an oligodeoxyribonucleotide, reaction products may conveniently be isolated by solvent-extraction techniques, up to about the tetranucleotide stage. 2-(4-Tritylphenyl)thioethanol (69) and 2-(4-tritylphenyl)sulphonylethanol (70) have been used for this purpose.119 For deblocking, (69) is first oxidized to (70) with iV-chlorosuccinimide and then removed with alkali. 

If 8-mercaptoadenosine-2, 3/-cyclic phosphate is treated with a phosphateactivating agent, e.g. diphenyl phosphorochloridate or tetraphenyl pyrophosphate, an oligomer is formed in which each phosphate is esterified by the 2 - and 3 -hydroxy-groups of one nucleoside residue and the 5 -hydroxy-group of the next. On 

Diester methods have been used to synthesize analogues of the initiator codon ApUpG in which the adenine residue has a fixed torsion angle, as for instance in (78),132 and triester methods have been used to prepare dinucleoside phosphates and codon analogues133 134 containing the hydroxyalkyl nucleosides 9-(4 -hydroxybutyl)-adenine (80), 9-(3 -hydroxypropyl)adenine (81), and 1 -(3 -hydroxypropyl)uracil (82), with a view to determining the effect of the achiral residues on the c.d. spectra. 

Chemical Synthesis.—Of the several new reviews of chemical synthesis of oligonucleotides, the most comprehensive is, fortunately, in English, and readily accessible.  

Ohtsuka, T. Tanaka, and M. Ikehara, Chem. and Pharm. Bull. Japan), 1976, 24, 2143 L. A. Alexandrova and J, Smrt, Coll. Czech. Chem. Comm., 1977, 42, 1595, 1686. 

Cashion, K. Porter, T. Cadger, G. Sathe, T. Tranquilla, H, Notman, and E. Jay, Tetrahedron Letters, 1976, 3769. 

Adenosine 5 -phosphorimidazolidate condenses in aqueous solution in the presence of divalent metal ions to form oligo(adenylic acid). Using divalent lead ions, as much as 57% condensation to oligo(A) has been reported studies on the di-and tri-nucleotide with RNase Tg show the internucleotide bonds to be mainly 2 - 5 -linked. The metals most efficient in catalysing condensation occupy an intermediate position in the classification as hard and soft acids and bases, and it is thought that they may co-ordinate to both base and phosphate. 

In a study on the potential of a series of substituted trityl groups in oligonucleotide synthesis, the (p-bromophenacyloxyphenyl)diphenyl-methyl group (28) appeared to have several advantages. On account of its size the chloride derived from (28) reacted only with 5 -hydroxy-groups of nucleosides and could easily be removed by the action of zinc and acetic 

A/ A -Dimethyl-p-phenylenediamine (30) has been attached to nucleotides to form basic phosphoramidates. These have been polymerized and the products purified by using a cationic rather than an anionic ion-exchange 

A number of polynucleotides containing atypical bases have been prepared during the past year either by polymerizing ribonucleoside diphosphates with polynucleotide phosphorylase or by polymerizing 

Oligoguanylic acids have been prepared from the 2, 3 -cyclic phosphates with the aid of RNase Tj and oligomers of 8-bromoguanylic acid have been obtained in this way. The latter are unobtainable by the polymerization of 8-bromoguanosine diphosphate or triphosphate as these substrates adopt the unfavourable 5y -conformation. 

Kaufmann, M. Fridkin, A. Zutra, and U. Z. Littauer, EuopeanJ. Biochem., 1971, 

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These early contributions were later supplemented by a comprehensive article on the mononucleotides by Ueda and Fox.4 The present article is an extension of these articles to chemical synthesis of oligo-and poly-nucleotides, and it is hoped that, in conjunction with the earlier articles, it will provide the organic chemist with a reasonable appreciation of some of the challenges, both past and present, of the synthetic chemistry of the nucleic acids. 

Gasparro EP, Eresco JR. Ultraviolet-induced 8,8 adenine dehydrodimers in oligo- and poly-nucleotides. Nucleic Acids Res. 1986 14 4239-4251. 

Nucleotides and Nucleic Acids Oligo- and Poly-nucleotides... 

In this year s review, it has only been possible to provide extensive coverage of the mononucleotide area. We hope to include a two-year review of oligo- and poly-nucleotide chemistry and nucleic acid structures in the next volume. 

Oligo- and poly-nucleotides 50 years of chemical synthesis , Reese, C. B., Org. Biomol. Chem., 2005, 3, 3851. 

Seliger H, Schmidt G. Derivatization with the 4-decyloxytrityl group as aid in the affinity chromatography of oligo- and poly-nucleotides. J Chromatogr 397 141-151, 1987. 

The Chemical Synthesis of Oligo- and Poly-nucleotides by the Phosphodies-ter Approach. Reese, C. B. Tetrahedron 19TO, 34, 3143-3179. 

Years of chemical s5mthesis of oligo- and poly-nucleotides 05OBC3851. 

A review of the chemical synthesis of oligo- and poly-nucleotides by the phosphotriester approach has appeared. ... 

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