- Synthesis and solution conformation studies of the modified nucleoside N4,2′-O-dimethylcytidine (m4Cm) and its analogues
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The dimethylated ribosomal nucleoside m4Cm and its monomethylated analogues Cm and m4C were synthesized. The conformations (syn vs anti) of the three modified nucleosides and cytidine were determined by CD and 1D NOE difference spectroscopy. The ribose sugar puckers were determined by the use of proton coupling constants. The position of modification (e.g., O vs N methylation) was found to have an effect on the sugar pucker of cytidine.
- Mahto, Santosh K.,Chow, Christine S.
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p. 8795 - 8800
(2008/12/23)
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- Anti-HCV nucleoside derivatives
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The present invention comprises novel and known purine and pyrimidine nucleoside derivatives which have been discovered to be active against hepatitis C virus (HCV). The use of these derivatives for the treatment of HCV infection is claimed as are the novel nucleoside derivatives disclosed herein.
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- Reductive monoalkylation of aromatic amines via amidine intermediates
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The convenience and efficiency of using amidines as intermediates in the reductive monoalkylation of aromatic amines has been demonstrated. This monoalkylation can be performed as either a two-step synthesis or a one-pot procedure. Several examples are presented which clearly demonstrate the utility of this new method for the methylation or ethylation of aromatic amines, including unprotected nucleosides.
- Zhang, Jianxing,Chang, Hui-Min,Kane, Robert R.
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p. 643 - 645
(2007/10/03)
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- Convenient intermediates for the preparation of C-4 modified derivatives of pyrimidine nucleosides
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4-(4-Nitrophenoxy)-1-(β-D-ribofuranosyl)pyrimidin-2(1H)-one 15, 5- methyl-4-(1,2,4-triazol-1-yl)-1-(β-D-2-deoxyribofuranosyl)pyrimidin-2(1H)- one 7a and 4-(4-nitrophenoxy)-1-(βD-2-deoxyribofuranosyl)pyrimidin-2(1H)- one 17a, respectively, have been prepared and are recommended as reactive intermediates for the preparation of derivatives of uridine, thymidine and 2'-deoxyuridine which are modified at C-4.
- Miah, Anwar,Reese, Colin B.,Song, Quanlai
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- Transformations of thiopyrimidine and thiopurine nucleosides following oxidation with dimethyldioxirane
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A general and convenient method for the synthesis of several pyrimidine and purine nucleosides by selective oxidation of thionucleosides with dimethyldioxirane is reported. Thioketo moieties in the C-4 position of the pyrimidine ring, and in the C-6, and C-8 positions of the purine ring are the domain of oxidative nucleophilic substitution. Thioketo moieties in the C-2 position of both purine and pyrimidine rings are the domain of desulfurization or formation of disulfides.
- Saladino, Raffaele,Mincione, Enrico,Crestini, Claudia,Mezzetti, Maurizio
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p. 6759 - 6780
(2007/10/03)
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- Synthesis and applications of oligoribonucleotides containing N4- methylcytidine
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The modified nucleotide N4-methylcytidine was incorporated in place of individual C residues in synthetic TAR and RRE RNA duplexes representing the binding sites for the HIV-1 tat and rev proteins respectively. In no case was cognate protein binding disrupted showing that the exocyclic amino groups of C residues are not sites of protein recognition.
- Grasby,Singh,Karn,Gait
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p. 1129 - 1132
(2007/10/02)
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- A New and Efficient Synthesis of Cytidine and Adenosine Derivatives by Dimethyldioxirane Oxidation of Thiopyrimidine and Thiopurine Nucleosides
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Dimethyldioxirane oxidation of thiopyrimidine and thiopurine nucleosides, in the presence of amines in stoichiometric amount, afforded selectively and under mild experimental conditions cytidine and adenosine nucleosides.
- Saladino, Raffaele,Crestini, Claudia,Bernini, Roberta,Frachey, Giuseppe,Mincione, Enrico
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p. 3053 - 3054
(2007/10/02)
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- Pyridyl groups for protection of the imide functions of uridine and guanosine. Exploration of their displacement reactions for site-specific modifications of uracil and guanine bases.
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For the protection of the O-4 function of uridine and the O-6 of guanosine, 2-, 3- and 4-hydroxypyridines, 2-pyridinethiol, 6-methyl-2-hydroxy- and 6-methyl-3-hydroxypyridines have been employed. These substituted pyridines gave pyridyl-N-and/or pyridyl-O-substituted derivatives, depending both upon the position of the hydroxyl and methyl groups in the pyridine ring, at the C-4 and the C-6 of the uracil and guanine residues, respectively. These groups were found to be good leaving groups for nucleophilic substitution reactions by amines, thiolates and oximate. If needed, the rate of these substitution reactions could be conveniently increased by almost 1000-fold by conversion of the pyridyl moiety to its methiodide.
- Zhou,Welch,Chattopadhyaya
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p. 806 - 816
(2007/10/02)
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- Unusual Competition between Nitrogen and Carbon Methylation of Nucleosides by Methyl Radical in Various Aqueous Media
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Five nucleosides, adenosine, guanosine, cytidine, thymidine, and uridine, were allowed to react with methyl radical produced by homolysis of tert-butyl peracetate.The extent and sites of reaction exhibited a marked dependence on the pH of the aqueous medium.In the region of pH 1-4, the major products arose from C-methylation of the nucleosides.The purines were more reactive than the pyrimidines under these acidic conditions.In the pH range of 4-10, the extent of C-methylation decreased steadily with increasing pH while N-methylated products arising from methylationof the ring nitrogen and/or exocyclic amino groups predominated.In this pH range, the pyrimidine nucleosides were the more reactive.Beyond pH 10, the extent of methylation diminished in all cases as decomposition of tert-butyl peracetate became rampant.The C-methylation occurs by way of an addition mechanism while N-methylation appears to proceed via radical abstraction of a hydrogen from the N-H group followed by combination with methyl radical.The implications of these reactivity and methylation patterns in radical carcinogenesis are discussed.
- Zady, Mona F.,Wong, John L.
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p. 2373 - 2377
(2007/10/02)
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- Pyrimidine nucleosides. 6. Syntheses and anticancer activities of N4 substituted 2,2' anhydronucleosides
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Some derivatives of N4 substituted 2,2' cyclo araC [N4 hydroxy, N4 methoxy, N4 methyl, and N4phenyl] which are potential carcinostatic nucleosides were prepared by introducing the 2,2' anhydro linkage
- Kanai,Ichino,Hoshi
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p. 1076 - 1078
(2007/10/04)
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