Abstract:The synthesis of cyclic di-, tri-, tetra-, penta- and hexa-thymidylic acids (16; n = 2, 3, 4, 5 and 6) and the cyclic hexadeoxyribonucleotide [d(CpCpTpApGpGp)], via the "filtration" approach, is reported. Some of the physical properties of the cyclic oligonucleotides are discussed, and their susceptibility to digestion in the presence of phosphorylytic enzymes has been studied.
“…One early example of this concept in short duplex DNAs was the addition of loops closing the ends to give dumbbell-like structures. − More recently there has been considerable interest in circular DNAs which lack this internally complementary structure (thus allowing them to bind other nucleic acids). Synthesis of cyclic DNAs and RNAs has been studied in many laboratories, − and recently a number of strategies for binding such cyclic molecules to nucleic acid targets have been described. − A circular oligonucleotide can bind a single-stranded target strand of RNA or DNA by forming standard Watson−Crick bonds. However, such binding is limited because of the helical twist of DNA: the strand being bound will therefore required to pass through the circle once per ∼10−12 bases of hybridization (corresponding to a turn of the helix, Figure ). ,, This is an unlikely event except when binding very short target strands.…”
“…One early example of this concept in short duplex DNAs was the addition of loops closing the ends to give dumbbell-like structures. − More recently there has been considerable interest in circular DNAs which lack this internally complementary structure (thus allowing them to bind other nucleic acids). Synthesis of cyclic DNAs and RNAs has been studied in many laboratories, − and recently a number of strategies for binding such cyclic molecules to nucleic acid targets have been described. − A circular oligonucleotide can bind a single-stranded target strand of RNA or DNA by forming standard Watson−Crick bonds. However, such binding is limited because of the helical twist of DNA: the strand being bound will therefore required to pass through the circle once per ∼10−12 bases of hybridization (corresponding to a turn of the helix, Figure ). ,, This is an unlikely event except when binding very short target strands.…”
“…There is great interest in constructs of oligonucleotides with unusual topologies. Among them, cyclic DNA and RNA were synthesized in the late 1980s, − and there appears to be a growing interest for them in several recent works. − Cyclic DNA and RNA present unusual chemical and biological properties in comparison with linear DNA and have been evaluated for several biological applications including antisense, triplex, and diagnostic applications. ,− Several methods have been developed for the synthesis of cyclic oligonucleotides using enzymatic or chemical protocols leading to cyclic oligonucleotides with phosphodiester, ,− phosphorothiolate diester, ,− disulfide, or oxime linkages. , 1 Synthesis of the Pentenyl Phosphoramidite of Thymidine…”
The synthesis of cyclic, branched, and bicyclic oligonucleotides was performed by copper-catalyzed azide-alkyne cycloaddition assisted by microwaves in solution and on solid support. For that purpose, new phosphoramidite building blocks and new solid supports were designed to introduce alkyne and bromo functions into the same oligonucleotide by solid-phase synthesis on a DNA synthesizer. The bromine atom was then substituted by sodium azide to yield azide oligonucleotides. Cyclizations were found to be more efficient in solution than on solid support. This method allowed the efficient preparation of cyclic (6- to 20-mers), branched (with one or two dangling sequences), and bicyclic (2 x 10-mers) oligonucleotides.
“…[1][2][3][4][5] The first cyclic DNAs were synthesized in the late 1980s, [1,[6][7][8][9] and new syntheses of cyclic DNAs and RNAs have been reported along the years. [1][2][3][4][5] The first cyclic DNAs were synthesized in the late 1980s, [1,[6][7][8][9] and new syntheses of cyclic DNAs and RNAs have been reported along the years.…”
Section: Introductionmentioning
confidence: 99%
“…Cyclic DNA and RNA exhibit unusual chemical and biological properties in comparison with linear ones and have been evaluated for several biological applications such as antisense, triplex, and diagnostic applications. [1][2][3][4][5] The first cyclic DNAs were synthesized in the late 1980s, [1,[6][7][8][9] and new syntheses of cyclic DNAs and RNAs have been reported along the years. Their synthesis has been performed by using enzymatic and chemical methods to afford phosphodiester, [1,[10][11][12][13] phosphorothiolate diester, [14][15][16][17] disulfide [18][19][20] oxime, [17,21] and, more recently, triazole linkers.…”
A solid support and two phosphoramidites exhibiting a phthalimide–oxy group were synthesized. First, after treatment with hydrazine, the resulting 5′‐ and 3′‐oxyamine oligonucleotides were conjugated with aldehyde derivatives by oxime ligation. Second, oligonucleotides exhibiting an oxyamine at each end were circularized by means of different dialdehydes. Cyclic oligonucleotides of different lengths (9 to 31‐mer) were rapidly obtained without the need of a template. Finally, a bicyclic oligonucleotide was synthesized starting form an oligonucleotide bearing three oxyamines, which reacted with a trialdehyde to form three oxime ligations.
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