- A novel nitration product formed during the reaction of peroxynitrite with 2',3',5'-tri-O-acetyl-7,8-dihydro-8-oxoguanosine: N-nitro-N'-[1-(2,3,5- tri-O-acetyl-β-D-erythro-pentofuranosyl)-2,4-dioxoimidazolidin-5- ylidene]guanidine
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A novel nitration product, formed during the reaction of peroxynitrite with 2',3',5'-tri-O-acetyl-7,8-dihydro-8-oxoguanosine, has been characterized using a combination of UV/vis, CD, and NMR spectroscopy and mass spectrometry. This compound has been identified as N-nitro-N'-[1-(2,3,5-tri- P-O-acetyl-β-D-erythro-pentofuranosyl)-2,4-dioxoimidazolin-5- ylidene]guanidine (IV). Upon base hydrolysis, IV releases nitroguanidine (IVa) and an intermediate, 1-(2,3,5-tri-O-acetyl-β-D-erythro- pentofuranosyl)-5-iminoimidazolidine-2,4-dione (IVb). This intermediate is ultimately hydrolyzed to the stable 3-(2,3,5-tri-O-acetyl-β-D-erythro- pentofuranosyl)oxaluric acid (IVc). IV can be reduced by sodium borohydride to a pair of stable diastereomers (IV(red)). The formation of this product is rationalized in terms of initial oxidation of 2',3',5'-tri-O-acetyl-7,8- dihydro-8-oxoguanosine to a quinonoid diimine intermediate, 3. Nucleophilic attack at C5 of 3 by peroxynitrite leads to formation of a C5-oxyl radical species, 5, which then undergoes a series of rearrangements to yield an ylidene radical, 7. Combination of this radical species with nitrogen dioxide results in the formation of product IV.
- Niles, Jacquin C.,Wishnok, John S.,Tannenbaum, Steven R.
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- Absorption Characteristics and Quantum Yields of Singlet Oxygen Generation of Thioguanosine Derivatives
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6-Thioguanine (1a) is considered to be photochemotherapeutic due to its specific characteristics of photosensitivity to UVA light and singlet molecular oxygen generation. To extend its phototherapeutic ability, two related thioguanines, 8-thioguanine (2a) and 6,8-dithioguanine (3a), have been designed and explored. Since the solubility of these thioguanines in dehydrated organic solvents is too poor to study, their triacetyl-protected ribonucleosides, that is, 2′,3′,5′-tri-O-acetyl-6-thioguanosine (1c), 2′,3′,5′-tri-O-acetyl-8-thioguanosine (2c) and 2′,3′,5′-tri-O-acetyl-6,8-dithioguanosine (3c) were prepared and investigated. The absorption maxima of 1c, 2c and 3c in acetonitrile were found at longer wavelengths than that of unthiolated guanosine (4c). Especially, 3c has the longest wavelength for absorption maximum and the highest value in terms of molar absorption coefficient among all thionucleobases and thionucleosides reported. These absorption properties were also well reproduced by quantum chemical calculations. Quantum yields of singlet oxygen generation of 2c and 3c were determined by near-infrared emission measurements to be as large as that of 1c. These results suggest that the newly synthesized thioguanosines, in particular 3c, can be further developed as a potential photosensitive agent for light-induced therapies.
- Miyata, Shoma,Yamada, Takeshi,Isozaki, Tasuku,Sugimura, Hideyuki,Xu, Yao–Zhong,Suzuki, Tadashi
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- Pyridine-free and solvent-free acetylation of nucleosides promoted by molecular sieves
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A practical method for the acetylation of purine and pyrimidine nucleosides employing a combination of acetic anhydride and potassium-exchanged molecular sieves is described. Besides the high yields obtained for the acylated nucleosides, the procedure is simple, inexpensive and environmentally benign, avoiding the use of pyridine or co-solvents as additives. Georg Thieme Verlag Stuttgart.
- Sá, Marcus Mandolesi,Meier, Lidiane
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- Selective C8-Metalation of Purine Nucleosides via Oxidative Addition
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8-Bromo-2′-deoxy-3′,5′-di-O-acetylguanosine (1), 8-bromo-2′,3′,5′-tri-O-acetylguanosine (2), 8-bromo-2′-deoxy-3′,5′-di-O-acetyladenosine (3), and 8-bromo-2′,3′,5′-tri-O-acetyladenosine (4) react with [Pd(PPh3)4] via a C8-Br oxidative addition to give the C8-palladated azolato complexes [5]-[8] featuring an unprotonated N7 ring nitrogen atom. The complexes feature diastereotopic trans-disposed triphenylphosphine ligands, which allowed the determination of 2JPP for complexes of the type trans-[PdL2(PPh3)2] (2JPP = 442 Hz for [7]). In addition, two complex molecules of [7] form a trans-Watson-Crick/Hoogsteen AA base pair in the solid state. N7-protonation of the guanosine-derived complexes [5] and [6] with HBF4·Et2O and of adenosine-derived complexes [7] and [8] using lutidinium triflate yields complexes [9]BF4 and [10]BF4 and complexes [11]OTf and [12]OTf bearing protic NH,NR-NHC ligands derived from guanosine and adenosine, respectively.
- Kampert, Florian,Brackemeyer, Dirk,Tan, Tristan Tsai Yuan,Ekkehardt Hahn
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p. 4181 - 4185
(2018/11/23)
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- Tautomerism in 8-Nitroguanosine Studied by NMR and Theoretical Calculations
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The guanine base in DNA, due to its low oxidation potential, is particularly sensitive to chemical modifications. A large number of guanine lesions have been characterized and studied in some detail due to their relationship with tissue inflammations. Nevertheless, one example of these lesions is the formation of 8-nitro-guanosine, but the NMR data of this compound was only partially interpreted. A comprehensive study of the two possible tautomeric forms, through a detailed characterization of this compound, has implications for its base pairing properties. The target compound was obtained through a synthetic sequence of five steps, where all intermediates were fully characterized using spectral data. The analysis of the two tautomers was then evaluated through NMR spectroscopy and theoretical calculations of the chemical shifts and NH coupling constants, which were also compared with the data from guanosine.
- Barbosa, Thaís M.,Rittner, Roberto,Alexander, Katie,Cosstick, Richard,Abraham, Raymond J.
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- Synthesis of 8-alkoxy-6-alkylamino-2-alkylthiopurine nucleosides with a straightforward multiple-functionalization strategy
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A straight forward strategy to synthesize purine nucleosides with multiple functionalization on 2-, 6-, and 8-positions has been developed successfully, which provides a series of 8-alkoxy-6-alkylamino-2-alkylthiopurine nucleosides in moderate to good yields for further biological and medical activity screening.
- Du, Hongguang,Sun, Xiaoyang,Yu, Mingwu,Tian, Miao,Li, Shunlai,Wang, Zhiqian
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p. 2949 - 2953
(2016/07/06)
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- RNA INCLUDING NUCLEOSIDE COMPOUND, METHOD FOR REGULATING AMOUNT OF PROTEIN PRODUCED FROM THE RNA, AND NUCLEOSIDE COMPOUND
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An RNA of the present invention is an RNA containing a 5′ cap structure and a coding region having a 5′ initiation codon and a 3′ stop codon on both ends of the coding region, the RNA having a nucleoside compound introduced at a site selected from among the 5′ cap structure and 10 bases from a 5′ end of the RNA, wherein the nucleoside compound is such that a group is attached to (i) a carbon atom at position 8 of a purine nucleus or (ii) a carbon atom at position 5 or 6 of a pyrimidine nucleus, the group being represented by formula (I): [in-line-formulae]A-X═X-#??(I)[/in-line-formulae] where A represents an aryl group or a heteroaryl group, # represents a site where the group represented by the formula (I) is attached to the carbon atom at the position 8 of the purine nucleus or the carbon atom at the position 5 or 6 of the pyrimidine nucleus, and two Xs, which are identical to or different from each other, each represents a nitrogen atom or CH whose H may be substituted by alkyl.
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Page/Page column
(2013/03/26)
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- Bromination at C-5 of pyrimidine and C-8 of purine nucleosides with 1,3-dibromo-5,5-dimethylhydantoin
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Treatment of the protected and unprotected nucleosides with 1,3-dibromo-5,5-dimethylhydantoin in aprotic solvents such as CH 2Cl2, CH3CN, or DMF effected smooth bromination of uridine and cytidine derivatives at C-5 of pyrimidine rings as well as adenosine and guanosine derivatives at C-8 of purine rings. Addition of Lewis acids such as trimethylsilyl trifluoromethanesulfonate enhanced the efficiency of bromination.
- Rayala, Ramanjaneyulu,Wnuk, Stanislaw F.
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experimental part
p. 3333 - 3336
(2012/07/30)
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- Bicyclic Compounds and Their Use
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The present invention provides fluorescent bicyclic compounds of the formula (I); wherein ring A, the broken lines -----, C1----C2, R4 and R1 are as defined herein. The invention also relates to nucleoside and nucleotide analogues of said compounds, and their use as biological markers.
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Page/Page column 20
(2009/12/23)
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- Nucleotides; Part XXXVI A New Synthesis of 9-(β-D-Ribofuranosyl)uric Acid and its 5'-Monophosphate
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Syntheses for 9-(β-D-ribofuranosyl)uric acid (16) and its 5'-monophosphate 14 have been achieved starting from guanosine and applying the 2-(?-nitrophenyl)ethyl group for protection of the aglycon moiety as well as the phosphate function.A more effficient and direct approach to 14 uses O6,O8-dibenzyl protection and phosphorylation by the Yoshikawa procedure.The various protected intermediates have been characterized by spectroscopic means and elemental analysis.
- Schulz, Bernd S.,Pfleiderer, Wolfgang
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p. 210 - 218
(2007/10/02)
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- A NEW SYNTHESIS OF 9-β-D-RIBOFURANOSYLURIC ACID AND ITS 5'MONOPHOSPHATE
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Synthesis for 9-β-D-ribofuranosyluric acid (16) and its 5'-monophosphate 14 starting from guanosine and by applying the p-nitrophenylethyl blocking group are described.
- Schultz, Bernd S.,Pfleiderer, Wolfgang
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p. 5421 - 5424
(2007/10/02)
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