- A new synthesis of oxanosine and 2'-deoxyoxanosine
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An easy and more efficient synthesis of oxanosine and 2'-deoxyoxanosine has been developed, a key step in the reported synthesis is a new photochemical transformation by UV irradiation of 1-hydroxy derivatives of inosine.
- De Napoli, Lorenzo,Di Fabio, Giovanni,Messere, Anna,Montesarchio, Daniela,Piccialli, Gennaro,Varra, Michela
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- Nucleosides and nucleotides. Part 207: Studies in the chemical conversion of the 4-carboxamide group of 5-amino-1-β-D-ribofuranosylimidazole-4-carboxamide (AICA-riboside). Application for the synthesis of 1-deazaguanosine
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A mild and versatile chemical conversion of the 4-carboxamide group of 5-amino-1-β-D-ribofuranosylimidazole-4-carboxamide (AICA-riboside) is described. The reaction of protected AICA-riboside with di-tert-butyl dicarbonate gave 5-[N,N-di-(tert-butoxycarbonyl)]-amino-1-(5-O-tert-butyldimethylsilyl-2,3-O-i sopropylidene-β-D-ribofuranosyl)imidazole-4-[N,N-di-(tert-butoxycarbonyl)]ca rboxamide in 71% yield. The resulting tetraBoc derivative was treated with sodium methoxide, benzylamine, or acetonitrile anion to give the corresponding methyl ester, N-benzylcarboxamide, or cyanoacetyl products. The 4-cyanoacetylimidazole derivative was converted into 1-deazaguanosine via an intramolecular cyclization. (C) 2000 Elsevier Science Ltd.
- Kojima, Naoshi,Minakawa, Noriaki,Matsuda, Akira
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- 2'-Deoxyisoinosine: Synthesis of a highly fluorescent nucleoside and its incorporation into oligonucleotides
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The synthesis of 2'-deoxyisoinosine (2a) and the related 2',3'- dideoxynucleosides 2b and 3 is reported. The 3'-phosphonate 4b as well as the phosphoramidite 4c were prepared and employed in solid-phase oligonucleotide synthesis.
- Seela,Chen
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- Synthesis of xanthosine 2-phosphate diesters via phosphitylation of the carbonyl group
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O2-Phosphodiesterification of xanthosine has been achieved by a one-pot procedure consisting of the phosphitylation of the 2-carbonyl group of appropriately protected xanthosine derivatives using phosphoramidites and N-(cyanomethyl)dimethylammonium triflate (CMMT), oxidation of the resulting xanthosine 2-phosphite triesters, and deprotection. In addition, a study on the hydrolytic stability of a fully deprotected xanthosine 2-phosphate diester has revealed that it is more stable at higher pH.
- Oka, Natsuhisa,Hirabayashi, Hiroki,Kumada, Kota,Ando, Kaori
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- Simple method for fast deprotection of nucleosides by triethylamine- catalyzed methanolysis of acetates in aqueous medium
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A straightforward methodology for deacetylation of protected ribonucleosides was developed based on triethylamine-catalyzed solvolysis in aqueous methanol. Reactions are completed in a few minutes under microwave irradiation and the free nucleosides are obtained in high yield after simple evaporation of volatiles. Other important features include the involvement of readily available reagents and the compatibility with diverse functional groups, which make this process very attractive for broad application.
- Meier, Lidiane,Monteiro, Gustavo C.,Baldissera, Rodrigo A.M.,Sa?, Marcus Mandolesi
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experimental part
p. 859 - 866
(2010/09/11)
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- Formation of 2-chloroinosine from guanosine by treatment of HNO2 in the presence of NaCl
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We investigated the reaction of Guo with nitrous acid in the presence of NaCl. When 1 mM Guo was incubated with 100 mM NaNO2 and 2 M NaCl in sodium acetate buffer at pH 3.2 and 37°C, 2-chloroinosine (2-Cl-Ino) was produced in addition to oxanosine (Oxo) and xanthosine (Xao). The yield of 2-Cl-Ino was 0.033 mM at an incubation time of 2 h. Under the same reaction conditions, GMP and dGuo gave rise to the corresponding 2-chloro derivatives with comparable yields. All the 2-chloro derivatives were fairly stable (t1/2>360 h) at physiological pH and temperature. To elucidate the reaction mechanism of the chlorination, the diazoate derivative of Guo, a reaction intermediate of the Guo-HNO2 system, was employed as a starting compound. When the diazoate was incubated with 2 M NaCl in a neutral solution, 2-Cl-Ino was produced in addition to Oxo and Xao. These results suggest that the 2-chloro derivatives can be produced from foodstuffs in the human stomach and may have potential importance as a carcinogen causing gastric cancer.
- Suzuki, Toshinori,Ide, Hiroshi,Yamada, Masaki,Morii, Takashi,Makino, Keisuke
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p. 2937 - 2941
(2007/10/03)
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- Reactions of Nitric Oxide with Amines in the Presence of Dioxygen
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Nitric oxide (NO), a multifaceted bioregulatory agent and an environmental pollutant, can effectively convert aromatic amines to the corresponding triazenes under aerobic conditions, but not under anaerobic conditions.Nucleic acid bases and nucleosides are also determinated via hydrolysis of the diazonium ion products with exposure to aerobic NO solution.A peroxynitrite radical or nitrogen dioxide is suggested to be the ultimate reactive species.
- Nagano, Tetsuo,Takizawa, Hiromasa,Hirobe, Masaaki
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p. 8239 - 8242
(2007/10/02)
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- Ionization of purine nucleosides and nucleotides and their components by 193-nm laser photolysis in aqueous solution: Model studies for oxidative damage of DNA 1
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The effect of 20-ns pulses of 193-nm laser light on aqueous solutions of purine bases, (2′-deoxy)nucleosides, and (2′-deoxy)nucleotides was investigated, and monophotonic ionization was observed. Although (deoxy)ribose and (deoxy)ribose phosphates are also ionized by 193-nm light, the photoionization of the (deoxy)nucleosides and -tides takes place predominantly (90%) at the purine moiety, due to the much higher extinction coefficients at 193 nm of the bases as compared to the (deoxy)ribose phosphates. The quantum yields of photoionization (φPl) of the purines are in the range 0.01 to 0.08, based on φ(Cl-) at 193 nm of 0.46. As shown by comparison with data obtained from pulse radiolysis, the ionized purines, i.e., the radical cations, deprotonate in neutral solution, yielding neutral radicals. The radical cation of 1-methylguanosine, produced by photoionization in oxygen-saturated aqueous solution, deprotonates with the rate constant 3.5 × 105 s-1. In the absence of oxygen, the hydrated electrons resulting from the photoionization react with the untransformed purine derivatives to yield the corresponding radical anions. As these are rapidly protonated by water (as concluded from pulse radiolysis), the photoionization in deaerated neutral solution results in two different neutral radicals: a deprotonated radical cation and a protonated radical anion.
- Candeias,Steenken
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p. 699 - 704
(2007/10/02)
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- Nucleoside Syntheses, XXII. Nucleoside Synthesis with Trimethylsilyl Triflate and Perchlorate as Catalysts
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The novel Lewis acids (CH3)3SiOSO2CF3 (5), (CH3)3SiOSO2C4F9 (6), and (CH3)3SiClO4 (4) are highly selective and efficient Friedel-Crafts catalysts for nucleoside formation from silylated heterocycles and peracylated sugars as well as for rearrangements of persilylated protected nucleosides.With basic silylated heterocycles these new catalysts give much higher yields of the natural N-1-nucleosides than with SnCl4.
- Vorbrueggen, Helmut,Krolikiewicz, Konrad,Bennua, Baerbel
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p. 1234 - 1255
(2007/10/02)
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