2341-22-2Relevant academic research and scientific papers
Role of the guanine N1 imino proton in the migration and reaction of radical cations in DNA oligomers
Ghosh, Avik K.,Schuster, Gary B.
, p. 4172 - 4173 (2007/10/03)
Oxidation of a guanine nucleobase to its radical cation in DNA oligomers causes an increase in the acidity of the N1 imino proton that may lead to its spontaneous transfer to N3 of the paired cytosine. This proton transfer is suspected of playing an important role in long-distance radical cation hopping in DNA and the decisive product-determining role in the reaction of the radical cation with H2O or O2. We prepared and investigated DNA oligomers in which certain deoxycytidines are replaced by 5-fluoro-2′-deoxycytidines (F5dC). The pKa of F5C was determined to be 1.7 units below that of dC, which causes proton transfer from the guanine radical cation to be thermodynamically unfavorable. Photoinitiated one-electron oxidation of the DNA by UV irradiation of a covalently attached anthraquinone derivative introduces a radical cation that hops throughout the oligomer and is trapped selectively at GG steps. The introduction of F5dC does not affect the efficiency of charge hopping, but it significantly reduces the amount of reaction at the GG sites, as revealed by subsequent reaction with formamidopyrimidine glycosylase. These findings suggest that transfer of the guanine radical cation N1 proton to cytosine does not play a significant role in long-range charge transfer, but this process does influence the reactions with H2O and/or O2. Copyright
A simple and efficient synthesis of puromycin, 2,2′-anhydro- pyrimidine nucleosides, cytidines and 2′,3′-anhydroadenosine from 3′,5′-O-sulfinyl xylo-nucleosides
Takatsuki, Ken-Ichi,Ohgushi, Sumito,Kohmoto, Shigeo,Kishikawa, Keiki,Yamamoto, Makoto
, p. 719 - 734 (2007/10/03)
Synthesis of antibiotics, puromycin and 3 ′-amino-3 ′-deoxy-N 6 ,N 6 -dimethyladenosine 11 was achieved by utilizing the cyclic sulfite 6a of the xylo -3 ′,5 ′-dihydroxy group as a new protective group. The key synthetic step is the deprotection of the sulfite moiety through the intramolecular cyclization of 2-α-carbamate 7 . In a similar manner, 2,2 ′-anhydro-pyrimidine nucleosides 15 , ribo -cytidines 17 and 2 ′,3 ′-anhydroadenosine 14 were prepared in high yields from the corresponding sulfites 4 , 5 , and 6b , respectively. Copyright Taylor & Francis Group, LLC.
A new protecting group '3′,5′-O-sulfinyl' for xylo-nucleosides. A simple and efficient synthesis of 3′-amino-3′-deoxyadenosine (a puromycin intermediate), 2,2′-anhydro-pyrimidine nucleosides and 2′,3′-anhydro-adenosine
Takatsuki, Ken-Ichi,Yamamoto, Makoto,Ohgushi, Sumito,Kohmoto, Shigeo,Kishikawa, Keiki,Yamashita, Haruhiro
, p. 137 - 140 (2007/10/03)
We developed a new protecting group, the cyclic sulfite for the protection of the 3′,5′-dihydroxy group of nucleosides. Seven cyclic sulfites, 4a-c, 5a-b, and 6a-b were prepared in high yields from the corresponding xylo-uridines 1 and 2, and xylo-adenosines 3 with thionyl chloride, respectively. Synthesis of the puromycin intermediate 8 was carried out by deprotection of the sulfite moiety through an intramolecular cyclization of the 2′-α-carbamate 7.
Anti-HCV nucleoside derivatives
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, (2008/06/13)
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.
Biochemical detection of cytidine protonation within RNA
Oyelere,Strobel
, p. 10259 - 10267 (2007/10/03)
Perturbation of active site functional group pK(a)s is an important strategy employed by protein enzymes to achieve catalysis. There is increasing evidence to indicate that RNAs also utilize functional group pK(a) perturbation for folding and reactivity. One of the best candidates for a functionally relevant pK(a) perturbation is the N3 of C (pK(a) 4.2), which could be sufficiently raised to allow protonation near physiological pH. Here we report the synthesis and use of a series of α-phosphorothioate tagged cytidine analogues whose altered N3 pK(a)s make it possible to efficiently detect functionally relevant protonation events by nucleotide analogue interference mapping. 6-Azacytidine (n6CαS) and 5-fluorocytidine (f5CαS) both have enhanced acidity at the N3 position (pK(a) 2.6 and 2.3, respectively) but leave the hydrogen bonding face of C otherwise unaffected. In contrast, pseudoisocytidine (ΨiCαS) is a charge neutral analogue that mimics the hydrogen bonding character of protonated C. To test the utility of these analogues, we characterized the C300+-G97-C277 mutant form of the Tetrahymena group I intron, which is predicted to require C300 protonation for ribozyme folding and reactivity. At neutral to alkaline pHs, C300 was the only site of n6CαS and f5Cαs interference within the intron, yet both interferences were rescued at acidic pH. Furthermore, ΨiCαS substitution at C300 resulted in enhanced activity at alkaline pHs, consistent with the presence of an N3 proton under the pH conditions studied. Interference mapping with these analogues provides an efficient and sensitive means to identify every site within an RNA where cytidine protonation is important for RNA function and may make it possible to identify C's that participate in general acid/base catalysis within ribozyme active sites.
19F NMR of RNA. The structural and chemical aspects of 5-fluoro-cytidine and -uridine labelling of oligoribonucleotides
Fischer,Gdaniec,Biala,Lozynski,Milecki,Adamiak
, p. 477 - 488 (2007/10/03)
Results of PM3 semiempirical calculation revealed that energy and hydrogen bonds geometry of 1-methyl-5-fluoro-uracil and -cytosine base-pairs with 9-methyladenine and -guanine respectively are virtually the same as for the natural bases. Analysis of proton coupling constants proved that the sugar puckering of 5-fluorouridine and 5-fluorocytidine is analogous to non-modified ribonucleosides. 5-Fluorocytidine was regioselectively introduced to oligoribonucleotides, prepared using 2'-O-tert-dimethylsilyl protection, via post-synthetic quantitative ammonolysis of 4-O-methyl-5-fluorouridine derived precursor.
Transformation of Uridine Derivatives into Cytidines via Selective Amination
Krug, A.,Schmidt, S.,Lekschas, J.,Lemke, K.,Cech, D.
, p. 835 - 842 (2007/10/02)
The synthesis of some 5-fluorosubstituted cytidine 2 derivatives via amination of corresponding uridine derivatives 1 is described. 5-Substituted 4-tetrazolo pyrimidinone derivatives 5 are key intermediates in the procedure.The method used is extended to other fluorinated starting materials, e.g. fluorinated uridinedinucleotides 7 or 2'-deoxy-2'-fluorouridine 9.The fluoro containing products are easily available by fluorination with elemental fluorine or hydrogene fluoride.
Reaction of Acetyl Hypofluorite with Pyrimidines. Part 3. Synthesis, Stereochemistry, and Properties of 5-Fluoro-5,6-dihydropyrimidine Nucleosides
Visser, Gerard W. M.,Herder, Renella E.,Noordhuis, Paul,Zwaagstra, Oene,Herscheid, Jacobus D. M.,Kanter, Frans J. J. de
, p. 2547 - 2554 (2007/10/02)
The reaction of acetyl hypofluorite (AcOF) with unprotected uracil and cytosine nucleosides in acetic acid or water has been studied using (18)F as a tracer.For the nucleosides in general two cis-diastereoisomers of both the 6-acetoxy-5-fluoro and 5-fluoro-6-hydroxy adducts were obtained, (1)H n.m.r. analysis of which showed that they all possessed the anti-conformation.The 6-acetoxy-5-fluoroadducts in the uracil nucleosides showed a remarkable stability and appeared to be interesting versatile compounds.They could be converted into their hitherto unknown corresponding 5-fluoro-6-hydroxy-O6,5'-anhydrocyclouracil nucleosides.For the cytosine nucleosides the 6-acetoxy-5-fluoro adducts were not observed, while the other cytosine adducts were found to rapidly deaminate at C-4 in water yielding the corresponding uracil analogues.Interestingly, even within a pair of diastereoisomers different deamination rates were observed.
Synthesis of O2,2′-cyclo-β-D-arabinofuranosyl- and β-D-arabinofuranosyl-5-fluorocytosine
Kvasyuk,Mikhailopulo,Barwolff,Cech
, p. 533 - 536 (2007/10/02)
Methods for the synthesis of 5-fluorocytosine by direct fluorination of cytidine tetraacetate with elementary fluorine in acetic acid and by amination of 5-fluorouridine triacetate by the action of sodium hydride and p-toluenesulfonyl chloride and subsequent ammonolysis were studied. 5-Fluorocytidine was converted to O2, 2′-cyclo-β-D-arabinofuranosyl-5-fluorocytosine by the successive action of acetylsalicylyl chloride and acetyl chloride in methanol to remove the protective groups. Removal of the protective groups by means of a methanol solution of ammonia gave β-D-arabinofuranosyl-5-fluorocytosine. The latter was also obtained by amination of β-D-arabinofuranosyl-5-fluorouracil tribenzoate.
