54 research outputs found

    Coordinatively unsaturated ruthenium complexes as efficient alkyne-azide cycloaddition catalysts

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    The performance of 16-electron ruthenium complexes with the general formula Cp*Ru(L)X (in which L = phosphine or N-heterocyclic carbene ligand; X = Cl or OCH2CF3) was explored in azide−alkyne cycloaddition reactions that afford the 1,2,3- triazole products. The scope of the Cp*Ru(PiPr3)Cl precatalyst was investigated for terminal alkynes leading to new 1,5-disubstituted 1,2,3-triazoles in high yields. Mechanistic studies were conducted and revealed a number of proposed intermediates. Cp*Ru- (PiPr3)(η2-HCCPh)Cl was observed and characterized by 1H, 13C, and 31P NMR at temperatures between 273 and 213 K. A rare example of N,N-Îș2-phosphazide complex, Cp*Ru(Îș2-iPr3PN3Bn)Cl, was fully characterized, and a single-crystal X-ray diffraction structure was obtained. DFT calculations describe a complete map of the catalytic reactivity with phenylacetylene and/or benzylazide.Publisher PDFPeer reviewe

    Contribution of N-heterocyclic carbene-containing catalysts in the nucleoside chemistry

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    Ces derniĂšres annĂ©es, les analogues nuclĂ©osidiques ont eu un rĂŽle majeur dans le traitement de maladies virales infectieuses tels le SIDA, les hĂ©patites, l’herpĂšs, la variole ou la grippe. Cependant, l’apparition de nouveaux virus ou de mutations virales ont renforcĂ© la nĂ©cessitĂ© de dĂ©velopper des antiviraux plus efficaces et plus rĂ©sistants. L’intensive recherche de dĂ©rivĂ©s nuclĂ©osidiques cliniquement actifs a permis l’émergence d’une multitude de nouvelles approches pour leurs synthĂšses. Parmi ce panel, les rĂ©actions catalysĂ©es par des mĂ©taux de transition tardifs font certainement partie des mĂ©thodes les plus importantes pour accĂ©der Ă  une large gamme de pharmacomodulations. Lors de ce projet de recherche, nous nous sommes intĂ©ressĂ©s Ă  la conception, la synthĂšse et la dĂ©couverte de nouveaux dĂ©rivĂ©s nuclĂ©osidiques en tant qu’antiviraux contre le virus de la variole. Pour ce faire, nous avons ciblĂ© des 1,2,3-triazolo-carbanuclĂ©osides en sĂ©rie racĂ©mique ou Ă©nantiosĂ©lective ainsi que des nuclĂ©osides phosphonates acycliques. Dans un effort de dĂ©veloppement et/ou d’amĂ©lioration de leurs mĂ©thodes de synthĂšse, nous avons Ă©galement Ă©tudiĂ© la contribution de complexes au ruthĂ©nium et au cuivre contenant un carbĂšne NhĂ©tĂ©rocyclique (CNH) dans des rĂ©actions de mĂ©tathĂšse croisĂ©e et de cycloaddition 1,3-dipolaire de Huisgen. Enfin, en vue d’obtenir des outils efficaces utilisables en synthĂšse nuclĂ©osidique, nous avons dĂ©veloppĂ©s des nouveaux complexes au palladium portant un ligand CNH et testĂ© leurs rĂ©activitĂ©s dans des rĂ©actions de Narylation de Buchwald-Hartwig et d’hydrogĂ©nation d’olĂ©fines.In the last decades, nucleoside analogues have played a major role in the treatment of viral infectious diseases, such as AIDS, hepatitis, herpes, smallpox or influenza. Nevertheless, the apparition of new or mutated viruses highlights the need of more potent and resistant antiviral therapeutics. The intense search for clinically useful nucleoside derivatives has resulted in a wealth of new approaches for their synthesis. Among them, latetransition metal-catalyzed reactions are certainly the most important methods to access variety of appealing pharmacomodulations. In this research project, we were interested in the conception, the synthesis and the discovery of new nucleoside derivatives as antiviral agents against smallpox viruses. Hence, we have targeted racemic or enantiomerically pure 1,2,3-triazolo-carbanucleosides as well as acyclic nucleoside phosphonates. In our effort into the development or/and the improvement of their synthetic methodologies, we have also studied the contribution of ruthenium and copper complexes bearing N-heterocyclic carbene (NHC) ligands in cross-metathesis and Huisgen 1,3-dipolar cycloaddition reactions. Finally, in order to obtain efficient tools useful in nucleoside synthesis, we have developed new NHC-containing palladium complexes and examined their reactivity in Buchwald-Hartwig N-arylation and olefins hydrogenation reactions

    Contribution des catalyseurs contenant un carbÚne N-hétérocyclique pour la chimie des nucléosides

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    In the last decades, nucleoside analogues have played a major role in the treatment of viral infectious diseases, such as AIDS, hepatitis, herpes, smallpox or influenza. Nevertheless, the apparition of new or mutated viruses highlights the need of more potent and resistant antiviral therapeutics. The intense search for clinically useful nucleoside derivatives has resulted in a wealth of new approaches for their synthesis. Among them, latetransition metal-catalyzed reactions are certainly the most important methods to access variety of appealing pharmacomodulations. In this research project, we were interested in the conception, the synthesis and the discovery of new nucleoside derivatives as antiviral agents against smallpox viruses. Hence, we have targeted racemic or enantiomerically pure 1,2,3-triazolo-carbanucleosides as well as acyclic nucleoside phosphonates. In our effort into the development or/and the improvement of their synthetic methodologies, we have also studied the contribution of ruthenium and copper complexes bearing N-heterocyclic carbene (NHC) ligands in cross-metathesis and Huisgen 1,3-dipolar cycloaddition reactions. Finally, in order to obtain efficient tools useful in nucleoside synthesis, we have developed new NHC-containing palladium complexes and examined their reactivity in Buchwald-Hartwig N-arylation and olefins hydrogenation reactions.Ces derniĂšres annĂ©es, les analogues nuclĂ©osidiques ont eu un rĂŽle majeur dans le traitement de maladies virales infectieuses tels le SIDA, les hĂ©patites, l’herpĂšs, la variole ou la grippe. Cependant, l’apparition de nouveaux virus ou de mutations virales ont renforcĂ© la nĂ©cessitĂ© de dĂ©velopper des antiviraux plus efficaces et plus rĂ©sistants. L’intensive recherche de dĂ©rivĂ©s nuclĂ©osidiques cliniquement actifs a permis l’émergence d’une multitude de nouvelles approches pour leurs synthĂšses. Parmi ce panel, les rĂ©actions catalysĂ©es par des mĂ©taux de transition tardifs font certainement partie des mĂ©thodes les plus importantes pour accĂ©der Ă  une large gamme de pharmacomodulations. Lors de ce projet de recherche, nous nous sommes intĂ©ressĂ©s Ă  la conception, la synthĂšse et la dĂ©couverte de nouveaux dĂ©rivĂ©s nuclĂ©osidiques en tant qu’antiviraux contre le virus de la variole. Pour ce faire, nous avons ciblĂ© des 1,2,3-triazolo-carbanuclĂ©osides en sĂ©rie racĂ©mique ou Ă©nantiosĂ©lective ainsi que des nuclĂ©osides phosphonates acycliques. Dans un effort de dĂ©veloppement et/ou d’amĂ©lioration de leurs mĂ©thodes de synthĂšse, nous avons Ă©galement Ă©tudiĂ© la contribution de complexes au ruthĂ©nium et au cuivre contenant un carbĂšne NhĂ©tĂ©rocyclique (CNH) dans des rĂ©actions de mĂ©tathĂšse croisĂ©e et de cycloaddition 1,3-dipolaire de Huisgen. Enfin, en vue d’obtenir des outils efficaces utilisables en synthĂšse nuclĂ©osidique, nous avons dĂ©veloppĂ©s des nouveaux complexes au palladium portant un ligand CNH et testĂ© leurs rĂ©activitĂ©s dans des rĂ©actions de Narylation de Buchwald-Hartwig et d’hydrogĂ©nation d’olĂ©fines

    Organic Electron Donors as Powerful Single-Electron Transfer Reducing Agents in Organic Synthesis

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    International audienceOne-electron reduction is commonly used in organic chemistry to achieve radical formation via the stepwise transfer of one or two electrons from a donor to an organic substrate. Beyond metallic reagents, Single-Electron Transfer reducers based on neutral organic molecules have emerged as an attractive novel source of reducing electrons. The past twenty years have thus seen the blossom of a particular class of organic reducing agents, the electron-rich olefins, and the multiplication of their applications in organic synthesis. These powerful neutral ground-state organic electron donors have since showed several significant advantages in the reduction of numerous organic substrates. This review gives an overview of the different types of organic donors and of their specific characteristics in organic transformations

    N-Heterocyclic carbenes (NHCs) containing N-C-palladacycle complexes : synthesis and reactivity in aryl amination reactions

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    Starting from the corresponding dimer, new saturated NHC-containing N,N-dimethyl biphenylamine (DMBPA) palladacycle complexes have been synthesized and fully characterized. Catalytic activity of these well-defined, air- and moisture-stable palladium(II) complexes was evaluated in the Buchwald-Hartwig amination involving a range of unactivated aryl chlorides. From a practical perspective, the reaction conditions required when using [(NHC)Pd(palladacycle)Cl] systems are very appealing. The organic biphenyl ligand used in the synthesis of the pallaclacycles has been synthesized using a Suzuki-Miyaura cross-coupling employing the novel palladacycle-NHC complexes
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