- One-Electron Redox Potentials of Purines and Pyrimidines
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One-electron redox potentials of some purine and pyrimidine derivatives were determined by pulse radiolysis from electron transfer equilibria involving their and other free radicals.The redox potentials were determined at pH 13 by using p-methoxyphenol (E=0.4 V), Trolox C (E=0.19 V), and tryptophan (E=0.56 V) as references.The lowest oxidation potential measured for DNA bases was guanosine (E=0.72 V vs.NHE), and the highest was for 1-methylpyrimidines (E ca. 1.6 V) Uric acid (E=0.26 V) and isobarbituric acid (E=0.13 V) were found to have the lowest potentials.
- Jovanovic, Slobodan V.,Simic, Michael G.
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- Cytosine modules in quadruple hydrogen bonded arrays
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Cytosine modules have been investigated for applications in supramolecular quadruple hydrogen bonded arrays. Notably, the importance of the C-5-H in the formation of unfolded and folded arrays by substitution to C-5-F was established. In addition, the incorporation of different alkyl chain lengths at N-1 and N-9 indicated that longer alkyl chains give rise to more of the unfolded rotamer, with the chain length and degree of unsaturation at N-1 having the major effect. Methyl cytosine modules were also able to readily form hetero-associated Upy-UCyt dimers as efficiently as the hexyl cytosine modules and a polyadipate telechelic polymer was used to prepare cytosine polymers.
- Greco, Elisabetta,Aliev, Abil E.,Lafitte, Valerie G. H.,Bala, Kason,Duncan, David,Pilon, Laura,Golding, Peter,Hailes, Helen C.
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- Gas-phase tautomers of protonated 1-methylcytosine. Preparation, energetics, and dissociation mechanisms
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Tautomers of 1-methylcytosine that are protonated at N-3 (1+) and C-5 (2+) have been specifically synthesized in the gas phase and characterized by tandem mass spectrometry and quantum chemical calculations. Ion 1+ is the most stable tautomer in aqueous and methanol solution and is likely to be formed by electrospray ionization of 1-methylcytosine and transferred in the gas phase. Gas-phase protonation of 1-methylcytosine produces a mixture of 1+ and the O-2-protonated tautomer (3+), which are nearly isoenergetic. Dissociative ionization of 6-ethyl-5,6-dihydro-1- methylcytosine selectively forms isomer 2+. Upon collisional activation, ions 1+ and 3+ dissociate by loss of ammonia and [C,H,N,O], whose mechanisms have been established by deuterium labeling and ab initio calculations. The main dissociations of 2+ following collisional activation are losses of CH2=C=NH and HN=C=O. The mechanisms of these dissociations have been elucidated by deuterium labeling and theoretical calculations. Copyright
- Yao, Chunxiang,Cuadrado-Peinado, Maria L.,Polasek, Miroslav,Turecek, Frantisek
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- SUBSTITUTED IMIDAZOPYRIMIDIN-5(6H)-ONES AS ALLOSTERIC MODULATORS OF MGLUR5 RECEPTORS
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In one aspect, the invention relates to imidazopyrimidin-5(6H)-one analogs, derivatives thereof, and related compounds, which are useful as positive allosteric modulators of the metabotropic glutamate receptor subtype 5 (mGluR5); synthetic methods for making the compounds; pharmaceutical compositions comprising the compounds; and methods of treating neurological and psychiatric disorders associated with glutamate dysfunction using the compounds and compositions. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.
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Paragraph 0527; 0528; 0529; 0530
(2013/09/26)
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- SUBSTITUTED IMADAZAPYRINIDIN-5(6H)-ONES AS ALLOSTERIC MODULATORS OF MGLUR5 RECEPTORS
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In one aspect, the invention relates to imidazopyrimidin-5(6H)-one analogs, derivatives thereof, and related compounds, which are useful as positive allosteric modulators of the metabotropic glutamate receptor subtype 5 (mGluR5); synthetic methods for making the compounds; pharmaceutical compositions comprising the compounds; and methods of treating neurological and psychiatric disorders associated with glutamate dysfunction using the compounds and compositions. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.
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Page/Page column 191-192
(2012/10/07)
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- Universal Base
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The present invention provides artificial universal base capable of base pairing nonspecifically with any of four kinds of natural nucleic acid bases (A, T, G, and C) without the function to specifically recognize pairing natural nucleic acid bases for base pair formation. Universal base capable of base paring nonspecifically with four kinds of natural nucleic acid bases, wherein the universal base has a structure represented by the following chemical formula: wherein R represents a monovalent group other than a hydrogen atom.
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Page/Page column 4-5
(2010/03/02)
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- Synthesis of modified pyrimidine bases and positive impact of chemically reactive substituents on their in vitro antiproliferative activity
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The antiproliferative activity screening on human tumor cell lines of a series of modified uracil and cytosine bases as well as some corresponding acyclonucleosides, and comparison of structure-activity relationship revealed the importance of chemical rea
- Noll, Steffi,Kralj, Marijeta,Suman, Lidija,Stephan, Holger,Piantanida, Ivo
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body text
p. 1172 - 1179
(2009/09/30)
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- Novel synthetic route to 1-substituted cytosines
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1-Alkylcytosines, cytidine and 2'-deoxy-5-methylcytidine were synthesized in good yields from appropriate 1-alkyluracils, uridine or thymidine derivatives by hydrogenation of 6-substituted tetrazolo[1,5-c]pyrimidin-5(6H)-ones 2 over 10% palladium on charcoal in methanol. Compounds 2 were obtained by the reaction of 1-substituted uracils 1 with sodium azide and phosphorus oxychloride in acetonitrile.
- Ciszewski,Celewicz,Golankiewicz
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p. 777 - 779
(2007/10/02)
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- Reactions with Dimethyl Carbonate, 5 Methylation of the Pyrimidine Bases of Nucleic Acids
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The methylation of the pyrimidine bases of nucleic acids by dimethyl carbonate is described compared to dimethyl sulphate.The reaction needs higher temperature, a base and the help of 18-crown-6 and DMF as cosolvent. - Keywords: Dimethyl Carbonate, Methylations, Pyrimidine Bases of Nucleic Acids
- Jansen, Helmut in de Wal,Lissel, Manfred
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p. 863 - 865
(2007/10/02)
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- The efficiency of diphenylalkylsulfonium salts as alkylating agents
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A series of the title reagents have been used for the alkylation of a number of nucleophiles including iodide, cyanide, thiocyanate and fluoride ions as well as ethyl acetoacetate, phenylacetonitrile and a variety of nitrogen heterocyclic compounds.The results compared favorably with literature methods.
- Badet, Bernard,Julia, Marc,Lefebvre, Christian
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p. 431 - 434
(2007/10/02)
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- Stereochemistry of the Formation of 4-Alkoxyimino-5,6-dihydro-6-alkoxyaminopyrimidin-2(1H)-ones from Cytosines and Hydroxylamines
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High resolution 1H and 19F n.m.r. data together with deuterium labelling studies are presented which reveal that the addition of hydroxylamines across the 5,6-double bond of cytosines is predominantly trans.The 4-alkoxyimino-5,6-dihydro-6-alkoxyaminopyrimidin-2(1H)-one products show syn/anti isomerism about the 4-alkoxyimino-group dependent on the substituent at N(3) (H or Me, respectively) and conformational changes throughout the molecules which are dependent on the substituents at N(1) (H or Me) and C(5) (H or F).
- Atkins, Paul J.,Hall, C. Dennis
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p. 155 - 160
(2007/10/02)
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- Mechanisms of Bromination of Uracil Derivatives. 6. Cytosine and N-Substituted Derivatives
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The reactions of bromine with cytosine, 1-methylcytosine, cytidine, and 3-methylcytosine in acidic aqueous sloutions have been studied.Initially adducts (5-bromo-5,6-dihydro-6-hydroxycytosines) are produced which are clearly observable by proton NMR, albeit in their protonated forms in the acidic media used.In time the adducts undergo elimination of water to give substitution products, 5-bromocytosines.Kinetic measurements of the initial reaction in the pH range 0-5 are consistent with the adducts resulting from rate-determining attack of bromine in the free base form of the cytosine substrates followed by capture of the cation so produced by water.An alternative mechanism involving first hydration and then bromine attack can be ruled out.
- Tee, Oswald S.,Kornblatt, Mary Judith,Berks, Charles G.
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p. 1018 - 1023
(2007/10/02)
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- N-Alkylation of Cytosine and Its Nucleosides with Trialkyl Phosphates
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Cytosine has been readily alkylated with trialkyl phosphates to give the corresponding N-alkyl derivatives, trimethyl phosphate being especially useful for the N-methylation of the base moiety of cytosine nucleosides.
- Hayashi, Masahiro,Yamauchi, Kiyoshi,Kinoshita, Masayoshi
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p. 277 - 278
(2007/10/02)
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- Fluoride ion catalyzed alkylation of purines, pyrimidines, nucleosides and nucleotides using alky halides.
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Alkyl halides react rapidly with purines and pyrimidines in the presence of fluoride ion. Alkylation of thymidine leads to novel dimeric nucleoside derivatives bridged through N3. Alkylation of thymidine mono and dinucleotides leads to alkylation at the base (N3) as well as diester and triester formation at the phosphate.
- Ogilvie,Beaucage,Gillen,Entwistle,Quilliam
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p. 1695 - 1708,1696, 1703
(2007/10/05)
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