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Accueil > Les équipes > Méthodes et Applications en Chimie Organique (MACO) > Publications

Publications

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2017



  • T. Driant, F. Nachon, C. Ollivier, P. - Y. Renard, et E. Derat, « On the Influence of the Protonation States of Active Site Residues on AChE Reactivation: A QM/MM Approach », ChemBioChem, vol. 18, nᵒ 7, p. 666-675.
    Résumé : Acetylcholinesterase (AChE), an enzyme of the serine hydrolase superfamily, is a mediator of signal transmission at cholinergic synapses by catalyzing acetylcholine cleavage into acetate and choline. This enzyme is vulnerable to covalent inhibition by organophosphate compounds (like VX). Covalent inhibition of AChE does not revert spontaneously. Known reactivator compounds have limited action in restoring catalytic activity. QM/MM simulations of VX-inhibited AChE reactivation by pralidoxime (2-PAM), a classical reactivator, were performed. These afforded a broad view of the effect of protonation states of active-site residues, and provide evidence for the role of Glu202, which needs to be protonated for reactivation to occur. In situ deprotonation of 2-PAM for both protonation states of Glu202 showed that His447 is able to deprotonate 2-PAM with the assistance of Glu202. Because the active site of serine hydrolases is highly conserved, this work provides new insights on the interplay between the catalytic triad residues and this glutamate, newly identified as protonatable.
    Mots-clés : acetylcholinesterase, Computational chemistry, MACO, organophosphate, POLE 1, protonation, QM/MM, reactivation.


  • L. Ferrand, Y. Lyu, A. Rivera-Hernández, B. J. Fallon, M. Amatore, C. Aubert, et M. Petit, « Hydroboration and Diboration of Internal Alkynes Catalyzed by a Well-Defined Low-Valent Cobalt Catalyst », Synthesis.
    Résumé : Thieme E-Books & E-Journals
    Mots-clés : MACO, POLE 1.


  • L. Ferrand, Y. Tang, C. Aubert, L. Fensterbank, V. Mouriès-Mansuy, M. Petit, et M. Amatore, « Niobium-Catalyzed Intramolecular Addition of O–H and N–H Bonds to Alkenes: A Tool for Hydrofunctionalization », Organic Letters, vol. 19, nᵒ 8, p. 2062-2065.
    Résumé : A convenient, versatile, and easy to handle intramolecular hydrofunctionalization of alkenes (C–O and C–N bonds formation) is reported using a novel niobium-based catalytic system. This atom economic and eco-friendly methodology provides an additional synthetic tool for the straightforward formation of valuable building blocks enabling molecular complexity. Various pyran, furan, pyrrolidine, piperidine, lactone, and lactam derivatives as well as spirocyclic compounds are produced in high yields and selectivities.
    Mots-clés : MACO, POLE 1.


  • C. Lévêque, V. Corcé, L. Chenneberg, C. Ollivier, et L. Fensterbank, « Photoredox/Nickel Dual Catalysis for the C(sp3)–C(sp3) Cross-Coupling of Alkylsilicates with Alkyl Halides », European Journal of Organic Chemistry, vol. 2017, nᵒ 15, p. 2118-2121.
    Résumé : Alkylsilicates were engaged under photoredox/nickel dual catalysis conditions with alkyl halides for the first time. The C(sp3)–C(sp3) cross-coupling products were obtained in moderate yields and were accompanied by the homocoupling products of the alkyl halide derivatives. These promising findings are strongly suggestive of the high synthetic potential of the dual catalytic approach for the forging of alkyl carbon–carbon bonds.
    Mots-clés : cross-coupling, C–C coupling, MACO, Nickel, photoredox catalysis, POLE 1, radical reactions.


  • A. Parrot, A. Bernard, A. Jacquart, S. A. Serapian, C. Bo, E. Derat, O. Oms, A. Dolbecq, A. Proust, R. Métivier, P. Mialane, et G. Izzet, « Photochromism and Dual-Color Fluorescence in a Polyoxometalate–Benzospiropyran Molecular Switch », Angewandte Chemie International Edition, vol. 56, nᵒ 17, p. 4872-4876.
    Résumé : The photophysical properties of a Keggin-type polyoxometalate (POM) covalently bounded to a benzospiropyran (BSPR) unit have been investigated. These studies reveal that both closed and open forms are emissive with distinct spectral features (λem (closed form)=530 nm, λem (open form)=670 nm) and that the fluorescence of the BSPR unit of the hybrid is considerably enhanced compared to BSPR parent compounds. While the fluorescence excitation energy of the BSPR reference compounds (370 nm) is close to the intense absorption responsible of the photochromic character (350 nm), the fluorescence excitation of the hybrid is shifted to lower energy (400 nm), improving the population of the emissive state. Combined NOESY NMR and theoretical calculations of the closed form of the hybrid give an intimate understanding of the conformation adopted by the hybrid and show that the nitroaryl moieties of the BSPR is folded toward the POM, which should affect the electronic properties of the BSPR.
    Mots-clés : density functional calculations, E-POM, fluorescence, MACO, molecular photoswitches, photochromism, POLE 1, POLE 2, Polyoxometalates.


  • S. Roy, B. Sharma, J. Pécaut, P. Simon, M. Fontecave, P. D. Tran, E. Derat, et V. Artero, « Molecular Cobalt Complexes with Pendant Amines for Selective Electrocatalytic Reduction of Carbon Dioxide to Formic Acid », Journal of the American Chemical Society, vol. 139, nᵒ 10, p. 3685-3696.
    Résumé : We report here on a new series of CO2-reducing molecular catalysts based on Earth-abundant elements that are very selective for the production of formic acid in dimethylformamide (DMF)/water mixtures (Faradaic efficiency of 90 ± 10%) at moderate overpotentials (500–700 mV in DMF measured at the middle of the catalytic wave). The [CpCo(PR2NR′2)I]+ compounds contain diphosphine ligands, PR2NR′2, with two pendant amine residues that act as proton relays during CO2-reduction catalysis and tune their activity. Four different PR2NR′2 ligands with cyclohexyl or phenyl substituents on phosphorus and benzyl or phenyl substituents on nitrogen were employed, and the compound with the most electron-donating phosphine ligand and the most basic amine functions performs best among the series, with turnover frequency >1000 s–1. State-of-the-art benchmarking of catalytic performances ranks this new class of cobalt-based complexes among the most promising CO2-to-formic acid reducing catalysts developed to date; addressing the stability issues would allow further improvement. Mechanistic studies and density functional theory simulations confirmed the role of amine groups for stabilizing key intermediates through hydrogen bonding with water molecules during hydride transfer from the Co center to the CO2 molecule.
    Mots-clés : MACO, POLE 1.

2016



  • M. Barbazanges, E. Caytan, D. Lesage, C. Aubert, L. Fensterbank, V. Gandon, et C. Ollivier, « Chiral Phosphate in Rhodium-Catalyzed Asymmetric [2+2+2] Cycloaddition: Ligand, Counterion, or Both? », Chemistry – A European Journal, vol. 22, nᵒ 25, p. 8553-8558.
    Résumé : Investigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium-catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4-diphenylphosphinobutane (dppb), and Ag(S)-TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X-type ligand.
    Mots-clés : chirality, CSOB, cycloaddition, homogeneous catalysis, ligand effects, MACO, POLE 1, POLE 3, Rhodium.


  • L. Chenneberg, C. Lévêque, V. Corcé, A. Baralle, J. - P. Goddard, C. Ollivier, et L. Fensterbank, « Single-Electron-Transfer Oxidation of Trifluoroborates and Silicates with Organic Reagents: A Comparative Study », Synlett, vol. 27, nᵒ 05, p. 731-735.

  • L. Chenneberg et C. Ollivier, « Tin-free Alternatives to the Barton-McCombie Deoxygenation of Alcohols to Alkanes Involving Reductive Electron Transfer », CHIMIA International Journal for Chemistry, vol. 70, nᵒ 1, p. 67-76.
    Résumé : Echoing the recent celebration of the fortieth anniversary of the Barton-McCombie reaction, this review aims to explore another facet of radical processes for deoxygenation of alcohols by considering SET (single electron transfer) reduction of carboxylic ester, thiocarbonate and thiocarbamate derivatives. Various protocols have been developed relying on the use of organic and organometallic SET reagents, electrochemical conditions, photoinduced electron transfer processes and visible-light photoredox catalysis. Applications to the synthesis of molecules of interest provide a glimpse into the scope of these different approaches.
    Mots-clés : Alcohols, deoxygenation, electron transfer, MACO, POLE 1, radicals, reduction.


  • B. J. Fallon, V. Corcé, M. Amatore, C. Aubert, F. Chemla, F. Ferreira, A. Perez-Luna, et M. Petit, « A well-defined low-valent cobalt catalyst Co(PMe3)4 with dimethylzinc: a simple catalytic approach for the reductive dimerization of benzyl halides », New Journal of Chemistry, vol. 40, nᵒ 12, p. 9912-9916.
    Résumé : Herein, we report the first catalytic version of a cobalt-catalysed reductive homocoupling of benzyl halides which proceeds with low catalyst loadings (0.5 to 5 mol%). By synthetizing each cobalt intermediate we demonstrate that reaction proceeds through two single electron transfers (SET) and that dimethylzinc is only involved in the regeneration of the catalytic species.
    Mots-clés : MACO, POLE 1, ROCS.


  • B. J. Fallon, E. Derat, M. Amatore, C. Aubert, F. Chemla, F. Ferreira, A. Perez-Luna, et M. Petit, « C2-Alkylation and Alkenylation of Indoles Catalyzed by a Low-Valent Cobalt Complex in the Absence of Reductant », Organic Letters, vol. 18, nᵒ 9, p. 2292-2295.
    Résumé : Herein an extremely versatile, well-defined, low-valent cobalt catalyst [Co(PMe3)4] capable of intermolecular and intramolecular imine-directed C2-alkylation and alkenylation of indoles is reported. The reaction proceeds in the absence of reducing agents or additives, affording a range of substituted indoles and dihydropyrroloindoles in high yields and regioselectivities. With the aid of deuterium labeling studies and DFT (Density Functional Theory) calculations, a mechanism is proposed that is based on a Ligand-to-Ligand Hydrogen Transfer pathway.
    Mots-clés : MACO, POLE 1, ROCS.


  • J. - P. Goddard, C. Ollivier, et L. Fensterbank, « Photoredox Catalysis for the Generation of Carbon Centered Radicals », Accounts of Chemical Research, vol. 49, nᵒ 9, p. 1924-1936.
    Résumé : ConspectusRadical chemistry has witnessed over the last decades important advances that have positioned it as a methodology of choice in synthetic chemistry. A number of great attributes such as specific reactivities, the knowledge of the kinetics of most elementary processes, the functional group tolerance, and the possibility to operate cascade sequences are clearly responsible for this craze. Nevertheless, at the end of the last century, radical chemistry appeared plagued by several hurdles to overcome such as the use of environmentally problematic mediators or the impossibility of scale up. While the concept of photocatalysis was firmly established in the coordination chemistry community, its diffusion in organic synthetic chemistry remained sporadic for decades until the end of the 2000s with the breakthrough merging of organocatalysis and photocatalysis by the MacMillan group and contemporary reports by the groups of Yoon and Stephenson. Since then, photoredox catalysis has enjoyed particularly active and intense developments. It is now the topic of a still increasing number of publications featuring various applications from asymmetric synthesis, total synthesis of natural products, and polymerization to process (flow) chemistry.In this Account, we survey our own efforts in this domain, focusing on the elaboration of new photocatalytic pathways that could lead to the efficient generation of C-centered functionalized alkyl and aryl radicals. Both reductive and oxidative manifolds are accessible through photoredox catalysis, which has guided us along these lines in our projects.Thus, we studied the photocatalytic reduction of onium salts such as sulfoniums and iodoniums for the production of the elusive aryl radical intermediates. Progressing to more relevant chemistry for synthesis, we examined the cleavage of C–O and the C–Br bonds for the generation of alkyl C-centered radicals. Activated epoxides could serve as valuable substrates of a photocatalyzed variant of the Nugent–RajanBabu–Gansäuer homolytic cleavage of epoxides. Using imidazole based carbamates, we could also devise the first photocatalyzed Barton–McCombie deoxygenation reaction. Finally, bromophenylacetate can be reduced using the [Au2(μ-dppm)2]Cl2 photocatalyst under UVA or visible-light. This was used for the initiation of the controlled atom transfer radical polymerization of methacrylates and acrylates in solution or laminate.Our next endeavors concerned the photocatalyzed oxidation of stabilized carbanions such as enolates of 1,3-dicarbonyl substrates, trifluoroborates, and more extensively bis-catecholato silicates. Because of their low oxidation potentials, the later have proved to be exquisite sources of radical entities, which can be engaged in diverse intermolecular reactions such as vinylation, alkynylation, and conjugate additions. The bis-catecholato silicates were also shown to behave as excellent partners of dual photoredox–nickel catalysis leading in an expeditious manner to libraries of cross coupling products.
    Mots-clés : MACO, POLE 1.


  • S. Guelen, M. Blazejak, V. Mouriès-Mansuy, et L. Fensterbank, « From Enynyl Esters to Functionalized Polycyclic Derivatives via Cycloisomerization and Post-Functionalization », Synthesis, vol. 48, nᵒ 19, p. 3199-3206.
    Résumé : Thieme E-Books & E-Journals
    Mots-clés : MACO, POLE 1.


  • J. Jacquet, S. Blanchard, E. Derat, M. D. - E. Murr, et L. Fensterbank, « Redox-ligand sustains controlled generation of CF3 radicals by well-defined copper complex », Chemical Science, vol. 7, nᵒ 3, p. 2030-2036.
    Résumé : A well-defined copper complex bearing iminosemiquinone ligands performs single electron reduction of an electrophilic CF3+ source into CF˙3 radicals. This redox behavior is enabled by the ligand which shuttles through two different redox states (iminosemiquinone and iminobenzoquinone) while the copper center is preserved as a Cu(II). This system was used in the trifluoromethylation of silyl enol ethers, heteroaromatics and in the hydrotrifluoromethylation of alkynes. This is the first example of cooperative redox catalysis for the controlled generation of CF˙3 radicals.
    Mots-clés : E-POM, MACO, POLE 1, POLE 2.


  • J. Jacquet, P. Chaumont, G. Gontard, M. Orio, H. Vezin, S. Blanchard, M. Desage-El Murr, et L. Fensterbank, « C−N Bond Formation from a Masked High-Valent Copper Complex Stabilized by Redox Non-Innocent Ligands », Angewandte Chemie International Edition, vol. 55, nᵒ 36, p. 10712-10716.
    Résumé : The reactivity of a stable copper(II) complex bearing fully oxidized iminobenzoquinone redox ligands towards nucleophiles is described. In sharp contrast with its genuine low-valent counterpart...
    Mots-clés : E-POM, MACO, POLE 1, POLE 2.


  • F. Jaroschik, A. Simonneau, G. Lemière, K. Cariou, N. Agenet, H. Amouri, C. Aubert, J. - P. Goddard, D. Lesage, M. Malacria, Y. Gimbert, V. Gandon, et L. Fensterbank, « Assessing Ligand and Counterion Effects in the Noble Metal Catalyzed Cycloisomerization Reactions of 1,6-Allenynes: a Combined Experimental and Theoretical Approach », ACS Catalysis, vol. 6, nᵒ 8, p. 5146-5160.
    Résumé : 1,6-Allenynes are useful mechanistic probes in noble-metal catalysis, since they can give rise to very distinct products in a highly selective fashion. Various cycloisomerization reactions have been described, and discrete mechanisms have been postulated. Of particular interest, whereas Alder-ene types of products can be obtained in a variety of ways using noble-metal catalysts (Au, Pt, Rh, ...), hydrindienes have been reported solely with gold and platinum under specific conditions. It was shown in a previous study that this intriguing transformation required the presence of chloride ligands at the active catalytic species. Herein, the factors governing the fate of 1,6-allenynes under cycloisomerization conditions have been studied more thoroughly, revealing a much more complex scenario. The nature of ligands, counterions, and metals was examined, showing that hydrindienes can be isolated in the absence of halides, using electron-rich, bulky triorganophosphines or carbene ligands. This crucial finding could also be used to access hydrindienes in high yields, not only with gold or platinum but also with silver. On the basis of mass spectrometry, NMR spectroscopy, and computations, refined mechanistic scenarios have been put forward, also rationalizing counterion effects. Notably, a metal vinylidene intermediate has been proposed for the formation of the hydrindiene derivatives. Finally, in the presence of tris((triphenylphosphine)gold)oxonium tetrafluoroborate as catalyst, a new pathway has been unveiled, involving gold alkyne σ,π complexes and leading to previously unobserved [2 + 2] cycloaddition compounds.
    Mots-clés : ARC, CSOB, MACO, POLE 1, POLE 2, POLE 3.


  • S. H. Kyne, C. Lévêque, S. Zheng, L. Fensterbank, A. Jutand, et C. Ollivier, « Iron(II) catalyzed reductive radical cyclization reactions of bromoacetals in the presence of NaBH4: optimization studies and mechanistic insights », Tetrahedron, vol. 72, nᵒ 48, p. 7727-7737.
    Résumé : 5-Exo-trig radical reductive cyclization reactions of bromoacetals are catalyzed by iron in the presence of the reducing agent NaBH4. Both iron(II) and iron(III) were found to effectively mediate these reactions. As shown by cyclic voltammetry, iron(III) can be reduced to an iron(II) precatalyst before passing through an identical reaction mechanism in which monoelectronic activation of the substrate would occur by an anionic hydridoiron(I) complex. Further studies have established that both the substrate (iodo- vs bromo-derivative) and the precatalytic mixture are decisive in determining the reaction outcome.
    Mots-clés : Electrochemistry, Homogenous catalysis, iron, MACO, NMR spectroscopy, POLE 1, Radical cyclization, reduction.


  • C. Lévêque, L. Chenneberg, V. Corcé, J. - P. Goddard, C. Ollivier, et L. Fensterbank, « Primary alkyl bis-catecholato silicates in dual photoredox/nickel catalysis: aryl- and heteroaryl-alkyl cross coupling reactions », Organic Chemistry Frontiers, vol. 3, nᵒ 4, p. 462-465.


  • C. Lévêque, L. Chenneberg, V. Corcé, C. Ollivier, et L. Fensterbank, « Organic photoredox catalysis for the oxidation of silicates: applications in radical synthesis and dual catalysis », Chemical Communications, vol. 52, nᵒ 64, p. 9877-9880.
    Résumé : Metal free photooxidation of alkyl bis(catecholato)silicates with the organic dye 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyano-benzene (4CzIPN) allows the smooth formation of alkyl radicals. The latter can be efficiently engaged either with radical acceptors to provide homolytic addition products or in photoredox/nickel dual catalysis reactions to obtain cross-coupling products.
    Mots-clés : MACO, POLE 1.


  • L. Meziane, C. Salzemann, C. Aubert, H. Gérard, C. Petit, et M. Petit, « Hcp cobalt nanocrystals with high magnetic anisotropy prepared by easy one-pot synthesis », vol. 8, nᵒ 44, p. 18640-18645.
    Résumé : Herein we describe the first synthesis of pure mono-disperse spherical hcp-nanocrystals ferromagnetic at room temperature. Our strategy, based on the simple combination of oleylamine and ClCo(PPh3)3, allows the one-pot synthesis of size-controlled hcp-nanocrystals. The size and shape of the nanocrystals can be tuned by varying the reaction time or the concentration.
    Mots-clés : MACO, POLE 1.


  • A. Rivera-Hernández, B. J. Fallon, S. Ventre, C. Simon, M. - H. Tremblay, G. Gontard, E. Derat, M. Amatore, C. Aubert, et M. Petit, « Regio- and Stereoselective Hydrosilylation of Unsymmetrical Alkynes Catalyzed by a Well-Defined, Low-Valent Cobalt Catalyst », Organic Letters, vol. 18, nᵒ 17, p. 4242-4245.
    Résumé : Herein, the use of a well-defined low-valent cobalt(I) catalyst [HCo(PMe3)4] capable of performing the highly regio- and stereoselective hydrosilylation of internal alkynes is reported. The reaction can be applied to a variety of hydrosilanes, symmetrical and unsymmetrical alkynes, giving in many cases a single hydrosilylation isomer. Experimental and theoretical studies suggest the key step to be a hydro-cobaltation and that the reaction proceeds through a classical Chalk–Harrod mechanism.
    Mots-clés : MACO, POLE 1.


  • A. Vanitcha, C. Damelincourt, G. Gontard, N. Vanthuyne, V. Mouriès-Mansuy, et L. Fensterbank, « Bis-phosphine allene ligand: coordination chemistry and preliminary applications in catalysis », Chemical Communications, vol. 52, nᵒ 41, p. 6785-6788.
    Résumé : A 1,3-bis-diphenylphosphine allene can give rise to new coordination complexes with palladium, platinum and gold metals. These complexes were fully characterized by NMR, HRMS and X-ray diffraction analysis. For gold(I), the corresponding dinuclear complex has been used in a series of diagnostic catalytic reactions and gave promising preliminary results in asymmetric catalysis.
    Mots-clés : MACO, POLE 1.


  • G. Vincent, S. Cheli, R. Martinez Mallorquin, A. Abramovitch, S. Beauvière, C. Gomez, F. Brebion, I. Marek, M. Malacria, J. P. Goddard, et L. Fensterbank, « Oxidation of bis-sulfinyl carbanions as the pivot of ionic/radical tandem reactions », Comptes Rendus Chimie, vol. 19, nᵒ 3, p. 403-411.
    Mots-clés : Alkylidene bis-sulfoxide, conjugate addition, MACO, POLE 1, Radical, Red-ox, Tandem.


  • Z. Xia, O. Khaled, V. Mouriès-Mansuy, C. Ollivier, et L. Fensterbank, « Dual Photoredox/Gold Catalysis Arylative Cyclization of o-Alkynylphenols with Aryldiazonium Salts: A Flexible Synthesis of Benzofurans », The Journal of Organic Chemistry, vol. 81, nᵒ 16, p. 7182-7190.
    Résumé : A new method for the arylative cyclization of o-alkynylphenols with aryldiazonium salts via dual photoredox/gold catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives and offers an efficient approach to benzofuran derivatives. The scope of the transformation is wide, and the limitations are discussed. The reaction is proposed to proceed through a photoredox-promoted generation of a vinylgold(III) intermediate that undergoes reductive elimination to provide the heterocyclic coupling adduct.
    Mots-clés : MACO, POLE 1.

2015



  • M. Amatore et C. Aubert, « Recent Advances in Stereoselective [2+2+2] Cycloadditions: Recent Advances in Stereoselective [2+2+2] Cycloadditions », European Journal of Organic Chemistry, vol. 2015, nᵒ 2, p. 265-286.
    Mots-clés : Asymmetric synthesis, chirality, Cyclotrimerization, MACO, POLE 1, polycycles, transition metals.


  • M. Amatore, C. Aubert, M. Barbazanges, M. D. - E. Murr, C. Ollivier, J. Rodriguez, et D. Bonne, « Stereoselective Synthesis of Six-Membered Carbocycles », in Stereoselective Multiple Bond-Forming Transformations in Organic Synthesis, John Wiley & Sons, Inc, p. 185-210.
    Résumé : This chapter reviews some selected recent advances regarding the rapid synthesis of six-membered carbocycles based on stereoselective multiple bond-forming transformations (MBFTs). The synthesis of six-membered carbocycles, which are subunits of a large variety of complex molecules, noticeably natural products, has long been pursued by organic chemists. Besides Diels–Alder cycloadditions, a large variety of other MBFTs to reach such cycles has been developed over the past years. Metal-mediated cycloadditions and cycloisomerizations, radical transformations, and cascades are part of the most efficient methods to construct multiple carbon–carbon bonds and six-membered rings in a single operation and, in most cases, in a chemo, regio, and stereoselective manner. The advent and the development of the organocatalysis by using stable and easily accessible organic catalysts have opened new complementary methodologies to radical and organometallic approaches and have offered alternative approaches for accomplishing the synthesis of complex molecules.
    Mots-clés : complex molecules, MACO, multiple bond-forming transformations (MBFTs), organocatalysis, POLE 1, six-membered carbocycles, stereoselective manner.


  • M. Augé, A. Feraldi-Xypolia, M. Barbazanges, C. Aubert, L. Fensterbank, V. Gandon, E. Kolodziej, et C. Ollivier, « Double-Stereodifferentiation in Rhodium-Catalyzed [2 + 2 + 2] Cycloaddition: Chiral Ligand/Chiral Counterion Matched Pair », Organic Letters, vol. 17, nᵒ 15, p. 3754-3757.
    Résumé : The first enantioselective metal-catalyzed [2 + 2 + 2] cycloaddition involving a double asymmetric induction has been devised. It relies on the use of an in situ generated chiral cationic rhodium(I) catalyst with a matched chiral ligand/chiral counterion pair. Careful optimization of the catalytic system, as well as of the reaction conditions, led to atroposelective [2 + 2 + 2] pyridone cycloadducts with high ee?s up to 96%. This strategy outperformed those previously described involving a chiral ligand only or a chiral counterion only.
    Mots-clés : MACO, POLE 1.


  • T. Cañeque, F. Gomes, T. T. Mai, G. Maestri, M. Malacria, et R. Rodriguez, « Synthesis of marmycin A and investigation into its cellular activity », Nature Chemistry, vol. 7, nᵒ 9, p. 744-751.
    Résumé : Anthracyclines such as doxorubicin are used extensively in the treatment of cancers. Anthraquinone-related angucyclines also exhibit antiproliferative properties and have been proposed to operate via similar mechanisms, including direct genome targeting. Here, we report the chemical synthesis of marmycin A and the study of its cellular activity. The aromatic core was constructed by means of a one-pot multistep reaction comprising a regioselective Diels–Alder cycloaddition, and the complex sugar backbone was introduced through a copper-catalysed Ullmann cross-coupling, followed by a challenging Friedel–Crafts cyclization. Remarkably, fluorescence microscopy revealed that marmycin A does not target the nucleus but instead accumulates in lysosomes, thereby promoting cell death independently of genome targeting. Furthermore, a synthetic dimer of marmycin A and the lysosome-targeting agent artesunate exhibited a synergistic activity against the invasive MDA-MB-231 cancer cell line. These findings shed light on the elusive pathways through which anthraquinone derivatives act in cells, pointing towards unanticipated biological and therapeutic applications.
    Mots-clés : Biomimetic synthesis, MACO, Natural products, POLE 1.


  • V. Corcé, L. - M. Chamoreau, E. Derat, J. - P. Goddard, C. Ollivier, et L. Fensterbank, « Silicates as Latent Alkyl Radical Precursors: Visible-Light Photocatalytic Oxidation of Hypervalent Bis-Catecholato Silicon Compounds », Angewandte Chemie International Edition, vol. 54, nᵒ 39, p. 11414-11418.
    Résumé : This works introduces hypervalent bis-catecholato silicon compounds as versatile sources of alkyl radicals upon visible-light photocatalysis. Using Ir[(dF(CF3)ppy)2(bpy)](PF6) (dF(CF3)ppy=2-(2,4-difluorophenyl)-5-trifluoromethylpyridine, bpy=bipyridine) as catalytic photooxidant, a series of alkyl radicals, including highly reactive primary ones can be generated and engaged in various intermolecular homolytic reactions. Based on cyclic voltammetry, Stern–Volmer studies, and supported by calculations, a mechanism involving a single-electron transfer from the silicate to the photoactivated iridium complex has been proposed. This oxidative photocatalyzed process can be efficiently merged with nickel-catalyzed C sp 2C sp 3 cross-coupling reactions.
    Mots-clés : hypervalent compounds, MACO, oxidation, photocatalysis, POLE 1, radicals, silicates.


  • B. de Courcy, E. Derat, et J. - P. Piquemal, « Bridging organometallics and quantum chemical topology: Understanding electronic relocalisation during palladium-catalyzed reductive elimination », Journal of Computational Chemistry, vol. 36, nᵒ 15, p. 1167-1175.
    Résumé : This article proposes to bridge two fields, namely organometallics and quantum chemical topology. To do so, Palladium-catalyzed reductive elimination is studied. Such reaction is a classical elementary step in organometallic chemistry, where the directionality of electrons delocalization is not well understood. New computational evidences highlighting the accepted mechanism are proposed following a strategy coupling quantum theory of atoms in molecules and electron localization function topological analyses and enabling an extended quantification of donated/back-donated electrons fluxes along reaction paths going beyond the usual Dewar–Chatt–Duncanson model. Indeed, if the ligands coordination mode (phosphine, carbene) is commonly described as dative, it appears that ligands lone pairs stay centered on ligands as electrons are shared between metal and ligand with strong delocalization toward the latter. Overall, through strong trans effects coming from the carbon involved in the reductive elimination, palladium delocalizes its valence electrons not only toward phosphines but interestingly also toward the carbene. As back-donation increases during reductive elimination, one of the reaction key components is the palladium ligands ability to accept electrons. The rationalization of such electronic phenomena gives new directions for the design of palladium-catalyzed systems. © 2015 Wiley Periodicals, Inc.
    Mots-clés : MACO, organometallics, POLE 1, topological analysis.


  • P. - A. Deyris, T. Cañeque, Y. Wang, P. Retailleau, F. Bigi, R. Maggi, G. Maestri, et M. Malacria, « Catalytic Semireduction of Internal Alkynes with All-Metal Aromatic Complexes », ChemCatChem, vol. 7, nᵒ 20, p. 3266-3269.
    Résumé : A simple catalytic method involving all-metal aromatic frameworks as precatalysts ensures an efficient route to (Z)-alkenes. Aromatic triangular palladium clusters were used to reduce internal alkynes without any trace of the formation of alkane side products. These trinuclear complexes provide a catalytic system that parallels the activity and selectivity of their best mononuclear peers, and the catalyst likely operates through complementary mechanisms.
    Mots-clés : alkynes, aromaticity, cluster compounds, hydrogenation, MACO, metallacycles, POLE 1.


  • B. J. Fallon, E. Derat, M. Amatore, C. Aubert, F. Chemla, F. Ferreira, A. Perez-Luna, et M. Petit, « C–H Activation/Functionalization Catalyzed by Simple, Well-Defined Low-Valent Cobalt Complexes », Journal of the American Chemical Society, vol. 137, nᵒ 7, p. 2448-2451.
    Résumé : A facile C?H activation and functionalization of aromatic imines is presented using low-valent cobalt catalysts. Using Co(PMe3)4 as catalyst we have developed an efficient and simple protocol for the C?H/hydroarylation of alkynes with an anti selectivity. Deuterium-labeling experiments, DFT calculations coupled with the use of a well-defined catalyst have for the first time shed light on the elusive black box of cobalt catalyzed C?H functionalization.
    Mots-clés : MACO, POLE 1, ROCS.


  • B. J. Fallon, J. - B. Garsi, E. Derat, M. Amatore, C. Aubert, et M. Petit, « Synthesis of 1,2-Dihydropyridines Catalyzed by Well-Defined Low-Valent Cobalt Complexes: C–H Activation Made Simple », ACS Catalysis, vol. 5, nᵒ 12, p. 7493-7497.
    Résumé : A convenient one-pot system has been developed, allowing the synthesis of highly substituted dihydropyridines via a C?H activation/6π-electrocyclization pathway. The reaction proceeds with high regioselectivity, and we disclose the first example of isolated dihydropyridines lacking substitution in the 2 position. Moreover, the use of a simple well-defined low-valent cobalt complex without the need for reducing agents or additives in combination with computational studies provides a clearer insight into the C?H activation pathway than was previously reported.
    Mots-clés : MACO, POLE 1.


  • L. Ferrand, N. Das Neves, M. Malacria, V. Mouriès-Mansuy, C. Ollivier, et L. Fensterbank, « Gold-catalyzed cycloisomerization of [3]-cumulenols », Journal of Organometallic Chemistry.


  • F. Gomes, V. Narbonne, F. Blanchard, G. Maestri, et M. Malacria, « Formal base-free homolytic aromatic substitutions via photoredox catalysis », Organic Chemistry Frontiers, vol. 2, nᵒ 5, p. 464-469.
    Résumé : We developed a simple and convenient method to assemble biaryls exploiting a photoredox catalyst and visible light. Diazonium salts generate aryl radicals that could then add on unactivated (hetero)arenes and the sequence eventually delivers products via formal homolytic aromatic substitutions. The direct C–H arylation of these usually unreactive substrates is achieved at room temperature using low catalyst loadings and shows broad functional group tolerance.
    Mots-clés : MACO, POLE 1.


  • T. N. Huan, E. S. Andreiadis, J. Heidkamp, P. Simon, E. Derat, S. Cobo, G. Royal, A. Bergmann, P. Strasser, H. Dau, V. Artero, et M. Fontecave, « From molecular copper complexes to composite electrocatalytic materials for selective reduction of CO <sub>2</sub> to formic acid », J. Mater. Chem. A, vol. 3, nᵒ 7, p. 3901-3907.


  • H. Lenormand, V. Corcé, G. Sorin, C. Chhun, L. - M. Chamoreau, L. Krim, E. - L. Zins, J. - P. Goddard, et L. Fensterbank, « Versatile Access to Martin’s Spirosilanes and Their Hypervalent Derivatives », The Journal of Organic Chemistry, vol. 80, nᵒ 6, p. 3280-3288.


  • F. Nzulu, S. Telitel, F. Stoffelbach, B. Graff, F. Morlet-Savary, J. Lalevée, L. Fensterbank, J. - P. Goddard, et C. Ollivier, « A dinuclear gold(I) complex as a novel photoredox catalyst for light-induced atom transfer radical polymerization », Polym. Chem., vol. 6, nᵒ 25, p. 4605-4611.


  • J. - P. Porcher, T. Fogeron, M. Gomez-Mingot, E. Derat, L. - M. Chamoreau, Y. Li, et M. Fontecave, « A Bioinspired Molybdenum Complex as a Catalyst for the Photo- and Electroreduction of Protons », Angewandte Chemie International Edition, vol. 54, nᵒ 47, p. 14090-14093.
    Résumé : A molybdenum–dithiolene–oxo complex was prepared as a model of some active sites of Mo/W-dependent enzymes. The ligand, a quinoxaline–pyran-fused dithiolene, mimics molybdopterin present in these active sites. For the first time, this type of complex was shown to be active as a catalyst for the photoreduction of protons with excellent turnover numbers (500) and good stability in aqueous/organic media and for the electroreduction of protons in acetonitrile with remarkable rate constants (1030 s−1 at −1.3 V versus Ag/AgCl). DFT calculations provided insight into the catalytic cycle of the reaction, suggesting that the oxo ligand plays a key role in proton exchange. These results provide a basis to optimize this new class of H2-evolving catalysts.
    Mots-clés : density functional calculations, dithiolene ligands, homogeneous catalysis, hydrogen evolution reaction, MACO, molybdenum, POLE 1.


  • C. Simon, M. Amatore, C. Aubert, et M. Petit, « Mild Niobium-Catalyzed [2 + 2 + 2] Cycloaddition of Sila-triynes: Easy Access to Polysubstituted Benzosilacyclobutenes », Organic Letters, vol. 17, nᵒ 4, p. 844-847.
    Résumé : A new and efficient synthesis of highly sensitive benzosilacyclobutenes has been developed. For the first time, these compounds can be synthesized in very high yields by a mild, unprecedented intramolecular niobium-catalyzed [2 + 2 + 2] cycloaddition of easily accessible tetrasubstituted sila-triynes. An easy access to highly functionalized benzosilacyclobutenes enlarging the number of potential applications in organic and material chemistry is described.
    Mots-clés : MACO, POLE 1.


  • A. Vanitcha, G. Gontard, N. Vanthuyne, E. Derat, V. Mouriès-Mansuy, et L. Fensterbank, « Synthesis of Allenes Bearing Phosphine Oxide Groups and Investigation of Their Reactivity toward Gold Complexes », Advanced Synthesis & Catalysis, vol. 357, nᵒ 10, p. 2213-2218.
    Résumé : A collection of phosphine oxide allenes has been prepared. Their coordination to gold(I) has been studied giving new coordination complexes when a pendant pyridine moiety was present. Alternatively, their gold(I)-catalyzed cycloisomerization has proven to be quite efficient. An almost complete axial-to-central chirality transfer in the cyclization process was observed, opening the potential access to valuable enantiopure phosphorus derivatives.
    Mots-clés : allenes, gold carbenes, Gold catalysis, MACO, phosphines, POLE 1.


  • Y. Wang, P. - A. Deyris, T. Caneque, F. Blanchard, Y. Li, F. Bigi, R. Maggi, S. Blanchard, G. Maestri, et M. Malacria, « A Simple Synthesis of Triangular All-Metal Aromatics Allowing Access to Isolobal All-Metal Heteroaromatics », Chemistry – A European Journal, vol. 21, nᵒ 35, p. 12271-12274.
    Résumé : A simple synthetic method allows the one-pot assembly of C3-symmetric, 44-core-valence-electron, triangular Pd or Pt clusters and their heterobimetallic mixed Pd/Pt analogues. These mixed metal complexes are the first examples of stable triangular all-metal heteroaromatics. In contrast to traditional heteroaromatic molecules formed combining main-group elements, they actually retain structural and electronic features of their homonuclear analogues.
    Mots-clés : aromaticity, E-POM, EPOM, ERMMES, Heterocycles, MACO, POLE 1, POLE 2.

2014

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