- Electrochemical Synthesis of 5-Selenouracil Derivatives by Selenylation of Uracils
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A simple and efficient electrochemical selenylation of uracils in the presence of NH4I for the synthesis of 5-selenouracils has been developed. This transformation was performed in the transition metal-free, oxidant-free, and aerobic conditions, providing a rapid and practical protocol to 5-selenouracil derivatives.
- Chen, Yan-Yan,Jiang, Cai-Na,Ma, Xian-Li,Wang, Qian,Xu, Yan-Li
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Read Online
- The Peculiar Case of the Hyper-thermostable Pyrimidine Nucleoside Phosphorylase from Thermus thermophilus**
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The poor solubility of many nucleosides and nucleobases in aqueous solution demands harsh reaction conditions (base, heat, cosolvent) in nucleoside phosphorylase-catalyzed processes to facilitate substrate loading beyond the low millimolar range. This, in turn, requires enzymes that can withstand these conditions. Herein, we report that the pyrimidine nucleoside phosphorylase from Thermus thermophilus is active over an exceptionally broad pH (4–10), temperature (up to 100 °C) and cosolvent space (up to 80 % (v/v) nonaqueous medium), and displays tremendous stability under harsh reaction conditions with predicted total turnover numbers of more than 106 for various pyrimidine nucleosides. However, its use as a biocatalyst for preparative applications is critically limited due to its inhibition by nucleobases at low concentrations, which is unprecedented among nonspecific pyrimidine nucleoside phosphorylases.
- Kaspar, Felix,Neubauer, Peter,Kurreck, Anke
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p. 1385 - 1390
(2021/01/29)
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- Thermodynamic Reaction Control of Nucleoside Phosphorolysis
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Nucleoside analogs represent a class of important drugs for cancer and antiviral treatments. Nucleoside phosphorylases (NPases) catalyze the phosphorolysis of nucleosides and are widely employed for the synthesis of pentose-1-phosphates and nucleoside analogs, which are difficult to access via conventional synthetic methods. However, for the vast majority of nucleosides, it has been observed that either no or incomplete conversion of the starting materials is achieved in NPase-catalyzed reactions. For some substrates, it has been shown that these reactions are reversible equilibrium reactions that adhere to the law of mass action. In this contribution, we broadly demonstrate that nucleoside phosphorolysis is a thermodynamically controlled endothermic reaction that proceeds to a reaction equilibrium dictated by the substrate-specific equilibrium constant of phosphorolysis, irrespective of the type or amount of NPase used, as shown by several examples. Furthermore, we explored the temperature-dependency of nucleoside phosphorolysis equilibrium states and provide the apparent transformed reaction enthalpy and apparent transformed reaction entropy for 24 nucleosides, confirming that these conversions are thermodynamically controlled endothermic reactions. This data allows calculation of the Gibbs free energy and, consequently, the equilibrium constant of phosphorolysis at any given reaction temperature. Overall, our investigations revealed that pyrimidine nucleosides are generally more susceptible to phosphorolysis than purine nucleosides. The data disclosed in this work allow the accurate prediction of phosphorolysis or transglycosylation yields for a range of pyrimidine and purine nucleosides and thus serve to empower further research in the field of nucleoside biocatalysis. (Figure presented.).
- Kaspar, Felix,Giessmann, Robert T.,Neubauer, Peter,Wagner, Anke,Gimpel, Matthias
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supporting information
p. 867 - 876
(2020/01/24)
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- Design and development of macrocyclization methods for compounds with potential tuberculocidal activity to decrease CYP450 liver cytochrome inhibition
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A procedure for macrocyclization of compounds with potential tuberculocidal activity was developed in order to obtaining compounds with a lower degree of inhibition of the key CYP 3A4 cytochrome.
- Vasilevich,Aksenova,Aksenova,Afanasyev
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p. 717 - 730
(2017/05/29)
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- Mtb PKNA/PKNB Dual Inhibition Provides Selectivity Advantages for Inhibitor Design to Minimize Host Kinase Interactions
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Drug resistant tuberculosis (TB) infections are on the rise and antibiotics that inhibit Mycobacterium tuberculosis through a novel mechanism could be an important component of evolving TB therapy. Protein kinase A (PknA) and protein kinase B (PknB) are both essential serine-threonine kinases in M. tuberculosis. Given the extensive knowledge base in kinase inhibition, these enzymes present an interesting opportunity for antimycobacterial drug discovery. This study focused on targeting both PknA and PknB while improving the selectivity window over related mammalian kinases. Compounds achieved potent inhibition (Ki ≈ 5 nM) of both PknA and PknB. A binding pocket unique to mycobacterial kinases was identified. Substitutions that filled this pocket resulted in a 100-fold differential against a broad selection of mammalian kinases. Reducing lipophilicity improved antimycobacterial activity with the most potent compounds achieving minimum inhibitory concentrations ranging from 3 to 5 μM (1-2 μg/mL) against the H37Ra isolate of M. tuberculosis.
- Wang, Tiansheng,Bemis, Guy,Hanzelka, Brian,Zuccola, Harmon,Wynn, Michael,Moody, Cameron Stuver,Green, Jeremy,Locher, Christopher,Liu, Aixiang,Gao, Hongwu,Xu, Yuzhou,Wang, Shaohui,Wang, Jie,Bennani, Youssef L.,Thomson, John A.,Müh, Ute
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supporting information
p. 1224 - 1229
(2017/12/26)
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- Direct Arylation of 5-Iodouracil and 5-Iodouridine with Heteroarenes and Benzene via Photochemical Reaction
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A method for the direct arylation of 5-iodouracil and 5-iodouridine was found to proceed in moderate yields. By irradiating mixtures of 5-iodouracil or 5-iodouridine and a series of five-membered heterocycles such as 1H-pyrrole, furan, 2-methylfuran, 1-methyl-1H-pyrrole, thiophene, as well as benzene in MeCN/H2O with a Hg lamp, 5-aryluracils and 5-aryluridines were synthesized. The reaction proceeded smoothly without the requirement of adding any transition metals or ligands.
- Yang, Qian,Wei, Tao,He, Yun,Liang, Yong,Zhang, Zun-Ting
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p. 953 - 960
(2015/11/23)
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- 5-Triazolyluracils and their N1-sulfonyl derivatives: Intriguing reactivity differences in the sulfonation of triazole N1′-substituted and N1′-unsubstituted uracil molecules
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We describe the synthesis of novel C5-triazolyl derived N1-sulfonylpyrimidines through CuI-catalyzed alkyne-azide cycloaddition followed by sulfonylation of the formed C5-triazolyl derivatives with various sulfonyl chlorides under basic conditions. In the latter step, an intriguing difference in the reactivity of the pyrimidine N1 was observed that depended on the nature of the substituent at a distant triazole N1′ site. The N1′-unsubstituted compounds gave very small amounts of sulfonylation products, whereas N1′-substituted systems produced high yields of the respective N1-sulfonyl-5-(1,2,3-triazol-4-yl)uracils. Computational analysis revealed a close correlation between the strength of the employed base catalysts and their abilities to increase the nucleophilicity of the uracil N1 atom through subsequent deprotonation, leading to more products. Following this step, the phosphazene tBu-P4 superbase was applied in the sulfonylation, resulting in exclusive formation of the triazole N1′-unsubstituted N1-sulfonylpyrimidines. The synthesis of C5-triazolyl-substituted pyrimidines and C5-triazolyl derived N1-sulfonylpyrimidines is described. Computational studies of the sulfonation step shed light on the differences in reactivity and revealed a connection between the strength of the employed base and its tendency to increase the nucleophilicity of the reacting uracil N1 atom by deprotonation.
- Saftic, Dijana,Vianello, Robert,?inic, Biserka
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p. 7695 - 7704
(2015/12/31)
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- Characterization of pyrimidine nucleoside phosphorylase of Mycoplasma hyorhinis: Implications for the clinical efficacy of nucleoside analogues
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In the present paper we demonstrate that the cytostatic and antiviral activity of pyrimidine nucleoside analogues is markedly decreased by a Mycoplasma hyorhinis infection and show that the phosphorolytic activity of the mycoplasmas is responsible for this. Since mycoplasmas are (i) an important cause of secondary infections in immunocompromised (e.g. HIV infected) patients and (ii) known to preferentially colonize tumour tissue in cancer patients, catabolic mycoplasma enzymesmay compromise efficient chemotherapy of virus infections and cancer. In the genome of M. hyorhinis, a TP (thymidine phosphorylase) gene has been annotated. This gene was cloned, expressed in Escherichia coli and kinetically characterized. Whereas the mycoplasma TP efficiently catalyses the phosphorolysis of thymidine (Km = 473 μM) and deoxyuridine (Km = 578 μM), it prefers uridine (K m =92 μM) as a substrate. Our kinetic data and sequence analysis revealed that the annotated M. hyorhinis TP belongs to the NP (nucleoside phosphorylase)-II class PyNPs (pyrimidine NPs), and is distinct from the NP-II class TP and NPI class UPs (uridine phosphorylases). M. hyorhinis PyNP also markedly differs from TP and UP in its substrate specificity towards therapeutic nucleoside analogues and susceptibility to clinically relevant drugs. Several kinetic properties of mycoplasma PyNP were explained by in silico analyses. The Authors Journal compilation
- Vande Voorde, Johan,Gago, Federico,Vrancken, Kristof,Liekens, Sandra,Balzarini, Jan
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experimental part
p. 113 - 123
(2012/10/23)
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- COMPOSITIONS AND METHODS FOR INHIBITING SPHINGOSINE KINASE
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Amidine analogs that can inhibit the activity of sphingosine kinase 1 and sphingosine kinase 2 (SphK1 and SphK2) are provided. The compounds can prevent angiogenesis in tumor cells.
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Page/Page column 40
(2009/12/27)
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- Rigid rod and tetrahedral hybrid compounds featuring nucleobase and nucleoside End-capped structures
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Being aimed at a new type of porous solids, a moduled design strategy of molecular tectons, making use of the conjugation between a shape defined artificial backbone and the bioinspired molecular fragments of nucleobases or nucleobase derivatives as functional end-caps, has been developed. This led to the formation of the new hybrid compounds 1-13 of linear and tetrahedral geometry, containing uracil, adenine, adenosine, guanosine and its acylated analogs as the sticky end-cap sites. The compounds were synthesized from a halogen or ethynyl substituted nucleobase component and the corresponding ethynylated spacer unit following a metal assisted coupling process as the key reaction step. X-Ray crystal structure analysis demonstrates that the parent compound 1 is a solvent complex with DMSO (1:2), showing the DMSO molecules incorporated in a hydrogen bonded layer structure. Specific dependencies of the fluorescence properties of the new compounds in solution on the structure of the molecules are reported. A selection of solid compounds has been studied in respect of their ability to adsorb organic vapours. They revealed significant differences both in the sorption capacity and the selectivity towards particular solvent vapours.
- Schindler, Diana,Eissmann, Frank,Weber, Edwin
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experimental part
p. 3549 - 3560
(2010/01/06)
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- Synthesis of (S,Z)-3-[(1H-indol-3-yl)methylidene]hexahydropyrrolo[1,2-a]pyrazin-4(1H)-one: an alternative, enaminone based, route to unsaturated cyclodipeptides
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A series of racemic and enantiopure (S,Z)-3-[(1H-indol-3-yl)methylidene]hexahydropyrrolo[1,2-a]pyrazin-4(1H)-one (cyclic Pro-ΔTrp) dipeptide analogues were prepared. Racemic analogues 6a-c were prepared by direct coupling of racemic cyclodipeptide enaminone (R,S)-5 with various indole derivatives. On the other hand, enantiopure analogues were prepared through a copper(I) catalyzed vinyl amidation reaction in which acyclic (S)-Pro-ΔTrp dipeptide analogues 20 and 21 were formed. Acyclic dipeptides were cyclized to enantiopure (S)-Pro-ΔTrp dipeptide analogues 24 and 25. For coupling reactions, vinyl bromides were prepared in several steps. From ethyl acetate (7), enaminone 8 was prepared and coupled with 2-methylindole and 2-phenylindole to give 9 and 10. Direct bromination of 3-(indole-3-yl)propenoates 9 and 10 at position 2 results in vinyl bromides 11 and 12. The Boc protecting group on the indole nitrogen 1′ in vinyl bromides 11 and 12 was introduced, before the copper(I) catalyzed coupling with N-Boc prolinamide 18 was performed. Enantiomeric purity of chiral intermediates and final products was determined mostly by HPLC or 1H NMR spectroscopy and X-ray diffraction.
- Wagger, Jernej,Gro?elj, Uro?,Meden, Anton,Svete, Jurij,Stanovnik, Branko
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p. 2801 - 2815
(2008/09/19)
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- Iodination of aryl amines in a water-paste form via stable aryl diazonium tosylates
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The diazotization of aryl amines at room temperature in paste form with NaNO2, p-TsOH and a small amount of water, followed by treatment with KI provides a new, simple, and effective route for the preparation of various aryl iodides. The water-paste and strong acid-free reaction conditions are environmentally friendly and compatible with acid-sensitive functional groups.
- Gorlushko, Dmitry A.,Filimonov, Victor D.,Krasnokutskaya, Elena A.,Semenischeva, Nadya I.,Go, Bong Seong,Hwang, Ho Yun,Cha, Eun Hye,Chi, Ki-Whan
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p. 1080 - 1082
(2008/09/18)
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- Practical synthesis of structurally important spirodiamine templates
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A general, concise, four-step synthetic sequence for the preparation of spirodiamine templates is described herein. Copyright Taylor & Francis Group, LLC.
- Tang,Qu,Xu,Ma,Chen, Shu-Hui,Li
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p. 3793 - 3799
(2008/02/10)
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- Dihydroxypyrimidine-4-carboxamides as novel potent and selective HIV integrase inhibitors
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Human immunodeficiency virus type-1 (HIV-1) integrase, one of the three constitutive viral enzymes required for replication, is a rational target for chemotherapeutic intervention in the treatment of AIDS that has also recently been confirmed in the clinical setting. We report here on the design and synthesis of N-benzyl-5,6-dihydroxypyrimidine-4-carboxamides as a class of agents which exhibits potent inhibition of the HIV-integrase-catalyzed strand transfer process. In the current study, structural modifications on these molecules were made in order to examine effects on HIV-integrase inhibitory potencies. One of the most interesting compounds for this series is 2-[1-(dimethylamino)-1-methylethyl]-N-(4-fluorobenzyl)-5,6-dihydroxypyrimidine- 4-carboxamide 38, with a CIC95 of 78 nM in the cell-based assay in the presence of serum proteins. The compound has favorable pharmacokinetic properties in preclinical species (rats, dogs, and monkeys) and shows no liabilities in several counterscreening assays, highlighting its potential as a clinically useful antiviral agent.
- Pace, Paola,Di Francesco, M. Emilia,Gardelli, Cristina,Harper, Steven,Muraglia, Ester,Nizi, Emanuela,Orvieto, Federica,Petrocchi, Alessia,Poma, Marco,Rowley, Michael,Scarpelli, Rita,Laufer, Ralph,Paz, Odalys Gonzalez,Monteagudo, Edith,Bonelli, Fabio,Hazuda, Daria,Stillmock, Kara A.,Summa, Vincenzo
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p. 2225 - 2239
(2007/10/03)
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- A facile synthesis of fluorophores based on 5-phenylethynyluracils
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Compact, fluorescent uracil aglycones and derivatives suitable for incorporation into the oligonucleotide mimic peptide nucleic acid (PNA) have been prepared by Sonogashira/Castro-Stephens coupling to monosubstituted phenylacetylenes. Cyclic 6-(phenyl)furo[2,3-d]pyrimidin-2(3H)-ones were accessed by the Ag+-catalyzed cyclization of the 5-alkynyluracil precursors. Although this reaction was sluggish, it gave quantitative chemical yields. Electron-rich alkynes, such as p-methoxyphenylethyne, cyclize much more rapidly than electron-deficient alkynes. Adjustment of the reaction conditions permitted the synthesis of p-nitrophenylfuranouracil in excellent yield. Georg Thieme Verlag Stuttgart.
- Hudson, Robert H. E.,Moszynski, Joanne M.
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p. 2997 - 3000
(2008/03/11)
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- Synthesis and biological evaluation of 5-(alkyn-1-yl)-1-(p-toluenesulfonyl) uracil derivatives
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Sonogashira coupling of 5-iodouracil (2) and trimethylsilylacetylene gave 5-(trimethylsilylethynyl)uracil (3), which was deprotected to give 5-ethynyluracil (4). Copper(I)-catalyzed cyclization of 4 gave furo[2,3-d]pyrimidin-2(3H)-one (5). Tosylation of 2 and 4 gave the 1-(p-toluenesulfonyl) derivatives 6 and 7, respectively. The tosylated compound 6 and trimethylsilylacetylene did not undergo Sonogashira coupling, and copper(I)-catalyzed cyclization of 7 did not occur. Coupling of 2 with several terminal alkynes gave 5-(alkyn-1-yl)uracil derivatives (9), which underwent tosylation to produce the targeted 5-(alkyn-1-yl)-1-(p-toluenesulfonyl)uracil compounds (11). Copper(I)-catalyzed cyclization of 9 gave the respective furopyrimidines (10) in low yields. Again, cyclization did not occur with the tosyl derivatives (11). Activity against varicella-zoster virus (VZV) was observed with longer-chain analogues of 9 and 11, and compound 7 showed activity against human cytomegalovirus (HCMV) at near cytotoxic levels.
- Janeba, Zlatko,Balzarini, Jan,Andrei, Graciela,Snoeck, Robert,De Clercq, Erik,Robins, Morris J.
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p. 580 - 586
(2007/10/03)
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- DNA-protein cross-linking: Model systems for pyrimidine-aromatic amino acid cross-linking
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We have synthesized simple model systems to explore the possibility of photo-cross-linking between the pyrimidine bases and the side chains of the aromatic amino acids. Thymine/phenylalanine and thymine/tyrosine models gave cross-links, and thymine/tryptophan models gave complex mixtures; the cytosine/phenylalanine model was unreactive. The quantum yields for the model cross-linking reactions were 18-46 times smaller than those for thymine dimer formation. Biphotonic excitation contributes little to the yield of these reactions.
- Sun, Guangxing,Fecko, Christopher J.,Nicewonger, Robert B.,Webb, Watt W.,Begley, Tadhg P.
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p. 681 - 683
(2007/10/03)
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- LIGANDS OF FOLLICLE STIMULATING HORMONE RECEPTOR AND METHODS OF USE THEREOF
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The present invention relates to compounds Formula I (I) that are modulators of the follicle stimulating hormone (FSH) receptor and are useful in the treatment of infertility and related disorders.
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Page/Page column 27
(2010/02/14)
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- A convenient protocol for the α-iodination of α,β- unsaturated carbonyl compounds with I2 in an aqueous medium
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A variety of cyclic and acyclic α,β-unsaturated carbonyl compounds undergo α-iodination exclusively, in high yields, with I 2, in aqueous THF catalyzed by DMAP and quinuclidine.
- Krafft, Marie E.,Cran, John W.
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p. 1263 - 1266
(2007/10/03)
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- Eco-friendly oxidative iodination of various arenes with sodium percarbonate as the oxidant http://www.mdpi.org
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Six easy laboratory procedures are presented for the oxidative iodination of various aromatics, mostly arenes, with either molecular iodine or potassium iodide (used as the sources of iodinating species, I+ or I 3+), in the presence of sodium percarbonate (SPC), a stable, cheap, easy to handle, and eco-friendly commercial oxidant.
- Zielinska, Agnieszka,Skulski, Lech
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p. 1307 - 1317
(2007/10/03)
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- A comparison of microwave-accelerated and conventionally heated iodination reactions of some arenes and heteroarenes, using ortho-periodic acid as the oxidant
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A fast and simple method for the oxidative iodination of some activated arenes and heteroarenes, either under microwave irradiation or by conventional heating, is reported, using diiodine and ortho-periodic acid as the oxidant. The reactions were carried out in hot 95% ethanol under a reflux condenser. For the microwave assisted reactions, the reaction times were always notably shortened, but the yields were nearly the same as those afforded by the conventional method.
- Sosnowski, Maciej,Skulski, Lech
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p. 401 - 406
(2007/10/03)
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- Nonmetal-catalyzed iodination of arenes with iodide and hydrogen peroxide
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Oxidative iodination of arenes was carried out with one equivalent of KI and two equivalents of 30% hydrogen peroxide in MeOH in the presence of strong acid. Reactions of various substituted anisoles, phenols and anilines, as well as mesitylene and uracil, were selective and effective with very good yields of isolated halogenated aromatic molecules.
- Iskra, Jernej,Stavber, Stojan,Zupan, Marko
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p. 1869 - 1873
(2007/10/03)
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- Pyrimidine phosphorylase as a target for imaging and therapy
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Thymine analogs and methods for their use as diagnostic and therapeutic agents for tumors.
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Page/Page column 5
(2008/06/13)
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- Eco-friendly Oxidative Iodination of Various Arenes with a Urea-Hydrogen Peroxide Adduct (UHP) as the Oxidant
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Three easy eco-friendly laboratory procedures are presented for the oxidative iodination of various activated and deactivated arenes with molecular iodine, in the presence of UHP (percarbamide), a stable, strongly H-bonded, solid urea-hydrogen peroxide adduct as the oxidant.
- Lulinski, Piotr,Kryska, Anna,Sosnowski, Maciej,Skulski, Lech
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p. 441 - 445
(2007/10/03)
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- Microwave-assisted C-5 iodination of substituted pyrimidinones and pyrimidine nucleosides
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Direct microwave-assisted iodination of several pyrimidinones and pyrimidine nucleosides with N-iodosuccinimide to give the corresponding 5-iodo derivatives is described. Application of this reaction to polymer-bound pyrimidinones was also investigated.
- Paolini, Lisa,Petricci, Elena,Corelli, Federico,Botta, Maurizio
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p. 1039 - 1042
(2007/10/03)
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- The use of Sonogashira coupling for the synthesis of modified uracil peptide nucleic acid
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Palladium-catalyzed Sonogashira coupling has been shown to be compatible with PNA monomers as illustrated by the reaction of 5-iodouracil peptide nucleic acid monomer (IU-PNA) with several terminal alkynes. These reactions have been performed in the solution phase and with IU-PNA linked to an insoluble polymer support. The results presented herein show that while the isolated yields from the solution phase chemistry are modest (38-53%), the yields of the resin-bound coupling reactions are essentially quantitative, at the monomer level. A selection of alkynes was used to install various additional functionality on the uracil nucleobase. Examples of a hydroxyl, protected thiol and protected amino group are given. Further, an example of derivatization of a resin-bound oligomer with a single IU insert is given.
- Hudson, Robert H.E,Li, Ge,Tse, Joseph
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p. 1381 - 1386
(2007/10/03)
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- 4-Pyrimidinyl-n-acyl-l phenylalanines
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Compounds of Formula I are disclosed, having activity as inhibitors of binding between VCAM-1 and cells expressing VLA-4, and accordingly useful for treating diseases whose symptoms and or damage are related to the binding of VCAM-1 to cells expressing VLA-4.
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- Improved, Acid-catalyzed Iodinating Procedures for Activated Aromatics with (Diacetoxyiodo)benzene as the Oxidant
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Improved procedures for the oxidative, acid-catalyzed iodination of benzene, iodobenzene and several activated aromatics are presented to give mono-, di-, or triiodinated products in 40-82 percent yields. The reactions proceeded at room temperature in the anhydrous systems: arene or hetarene/diiodine/(diacetoxyiodo)benzene (2)/glacial acetic acid/acetic anhydride, acidified with catalytic amounts of concd. (98 percent) H2SO4. Within at most 15 minutes the iodine coloration faded; the following workups are explained. A similar treatment with dibromine gave tribromomesitylene (65 percent), dibromodurene (62 percent), and 2,7-dibromofluoren-9-one (73 percent). A review on the aromatic halogenation reactions with organic trivalent iodine reagents as the oxidants is presented below.
- Kryska, Anna,Skulski, Lech
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p. 2501 - 2517
(2007/10/03)
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- 5-Fluorouracil derivatives
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Novel compounds comprising 5-fluorouracil or 5-fluorouridine covalently linked to 5-ethynyluracil, 5-ethynyluridine or 5-propynyluracil and pharmaceutical compositions comprising such compounds are disclosed.
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- Novel α-iodination of functionalized ketones with iodine mediated by bis(tetra-n-butylammonium) peroxydisulfate
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α,β-Unsaturated ketones, β-keto esters and uracil derivatives react with iodine in the presence of bis(tetra-n-butylammonium) peroxydisulfate under mild conditions in MeCN at 25°C to give the corresponding α-iodinated products in good yields.
- Whang, Je Pil,Yang, Seung Gak,Kim, Yong Hae
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p. 1355 - 1356
(2007/10/03)
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- Aromatic iodination of activated arenes and heterocycles with lead tetraacetate as the oxidant
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An easy, cheap and fairly quick laboratory method is presented for aromatic iodination of some highly activated arenes and heterocycles with molecular iodine in the presence of either pure lead tetraacetate dissolved in glacial acetic acid, or with the same oxidant but prepared in situ from Pb3O4 dissolved in hot AcOH/Ac2O prior to the iodination. 4-Bromo- and 2,4-dibromoanisoles are obtained from anisole by the respective oxidative bromination.
- Krassowska-Swiebocka,Lulinski,Skulski
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p. 926 - 928
(2007/10/02)
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- 4'-substituted nucleosides
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Nucleosides compounds of Formula I: STR1 wherein B is a purine or a pyrimidine; X and X' are H; Y is H; Y' is OH, F or H; or Y' and X' together makes a bond; Z is STR2 where n is zero, one, two or three; or Y' and Z together form a cyclic phosphate ester; Z' is --CN, --CH3, CH2 N3 or --CH2 J, where J is a halogen atom; or Z' and Y' together are --CH2 O--; and pharmaceutically acceptable esters, ethers, amides, N-acyl moieties and salts thereof.
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- Preparation of thionucleosides
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The invention relates to the preparation of homochiral thiolactones which have application in the synthesis of 3?- and 4?- thionucleosides. Substituents on the thiolactone can be used to influence the configuration of the C-1? position in the final nucleoside. Configuration at the C-4? position is controlled by use of the appropriate homochiral glycidol as starting material in the synthesis of the thiolactone. This process also offers the possibility of introducing substituents diastereoselectively in the C-2? and C-3? positions.
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- In-cell Indirect Electrochemical Halogenation of Pyrimidine Bases and their Nucleosides to 5-Haloderivatives
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Reaction of anodically generated "halonium" species (LiX or Bu4NX, LiClO4, MeCN, Pt/Pt; I2, LiClO4, MeCN) with pyrimidine bases and their nucleosides leads to 5-halo compounds in good yields.
- Palmisano, G.,Danieli, B.,Santagostino, M.,Vodopivec, B.,Fiori, G.
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p. 7779 - 7782
(2007/10/02)
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- Cerium(IV)-Mediated Halogenation at C-5 of Uracil Derivatives
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Treatment of protected uracil nucleosides 1 or 2 with elemental iodine or metal halogenides and ceric ammonium nitrate (CAN) at 80 deg C gave the corresponding protected 5-halouracil nucleosides 3a-f in excellent yields.Treatment of the resulting crude 3a-f with 0.1 M NaOMe/MeOH at ambient temperature gave the corresponding 5-halouridines 4a-f in high overall yields from 1 or 2.Further, 5-halouraciles 9a-f were prepared in good yields by treatment of 1,3-dimethyluracil (7) or uracil (8) with elemental iodine, metal halogenides, or hydrochloric acid and CAN.Halouridines 4a-e also were obtained in good yields by treatment of unprotected uracil nucleosides 5 or 6 with halogen sources as above and CAN.
- Asakura, Jun-ichi,Robins, Morris J.
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p. 4928 - 4933
(2007/10/02)
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- NOVEL SYNTHESIS OF 5-HALOURACILS FROM 5-MERCURI-2,4-DIMETHOXYPYRIMIDINES
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Direct C-mercuration of 2,4-dimethoxypyrimidine with mercury (II) acetate has been shown to give the 5-mercuri-derivative, which is readily converted, either directly or via 5,5'-mercuribis (2,4-dimethoxypyrimidine), into the 5-halo derivatives.Hydrolysis of the latter with hydrochloric acid affords the 5-halouracils.
- Skul'ski, L.,Kuyava, A.,Vrochin'ski, P.
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p. 205 - 208
(2007/10/02)
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- AN EFFICIENT METHOD FOR THE IODINATION OF C5-POSITION OF DIALKOXY PYRIMIDINES AND URACIL BASES
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N-Iodosuccinimide in trifluoroacetic acid and trifluoroacetic anhydride was found to be an excellent reagent for the conversion of 2,4-dialkoxy pyrimidines to 2,4-dialkoxy-5-iodopyrimidines.Iodination at C5-position of uracil and its derivatives was also accomplished with the above reagent.
- Das, Biswajit,Kundu, Nitya G.
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p. 855 - 868
(2007/10/02)
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- A SELECTIVE AND EFFICIENT METHOD FOR THE DEPROTECTION OF N-BENZYLOXYMETHYL (BOM) PROTECTING GROUPS FROM PYRIMIDINE AND DIHYDROPYRIMIDINE RING SYSTEMS
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N1,N3-dibenzyloxymethyl derivatives of pyrimidines and dihydropyrimidines have been successfully deprotected by using trifluoroacetic acid (TFA).These N-BOM derivatives can be selectively removed from a variety of derivatives including nucleosides and compounds which are sensitive to base and reducing conditions.
- DeFrees, Shawn A.,Reddy, Kalakota S.,Cassady, John M.
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p. 213 - 220
(2007/10/02)
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- IODO- AND CHLORODEMERCURATION OF 5,5'-MERCURIBISURACILS
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The direct C mercuration in the 5 position of 1-acetyluracil by means of mercury(II) trifluoroacetate in anhydrous acetonitrile is described.The intermediately formed 1-acetyl-5-trifluoroacetoxymercuriuracil, without isolation, was subjected to symmetrization by the action of potassium iodide.The acetyl groups were then readily split out by the action of water.The resulting 5,5'-mercuribisuracil (50percent yield) forms 5-iodo- or 5-chlorouracil in 93percent or 72percent yields, respectively, under the influence of an aqueous KI3 solution or excess pure liquid S2Cl2.
- Wroczynski, P.,Kujawa, A.,Skul'ski, L.
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p. 322 - 325
(2007/10/02)
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- The bromination and iodination of N1-substituted uracils
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Reaction of N1-substituted uracils with bromine in water at pH=7 leads to 5-bromo-6-hydroxy-5,6-hydrouracils.For different N1-substituents these products were isolated and the relatively stable derivatives were characterized by 1H NMR and mass spectroscopy.On electrophilic iodination with iodide and chloramine-T in water no indications were obtained for the formation of such dihydrouracils except for uridine and deoxyuridine.However, on reaction of N1-substituted uracils with N-iodosuccinimide in CHCl3 containing ethanol, or in ethanol, 5-iodo-6-ethoxy-5,6-dihydrouracils could be isolated as reaction products.
- Bakker, Cees N. M.,Kaspersen, Frans M.
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p. 267 - 271
(2007/10/02)
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