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

Publications

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2019



  • A. Cartier, E. Levernier, V. Corcé, T. Fukuyama, A. - L. Dhimane, C. Ollivier, I. Ryu, et L. Fensterbank, « Carbonylation of Alkyl Radicals Derived from Organosilicates through Visible-Light Photoredox Catalysis », Angewandte Chemie International Edition, vol. 58, nᵒ 6, p. 1789-1793, 2019.
    Résumé : Primary, secondary, and tertiary alkyl radicals formed by the photocatalyzed oxidation of organosilicates underwent efficient carbonylation with carbon monoxide (CO) to give a variety of unsymmetrical ketones. This study introduces the possibility of radical carbonylation under a photooxidative regime.
    Mots-clés : carbonylation, CHEMBIO, MACO, photocatalysis, POLE 1, POLE 3, radicals, silicates, three-component reactions.


  • F. Célerse, L. Lagardère, E. Derat, et J. - P. Piquemal, « Massively Parallel Implementation of Steered Molecular Dynamics in Tinker-HP: Comparisons of Polarizable and Non-Polarizable Simulations of Realistic Systems », Journal of Chemical Theory and Computation, vol. 15, nᵒ 6, p. 3694-3709, juin 2019.
    Résumé : Steered molecular dynamic (SMD) is a powerful technique able to accelerate rare event sampling in Molecular Dynamics (MD) simulations by applying an external force to a set of chosen atoms. Despite generating nonequilibrium simulations, SMD remains capable of reconstructing equilibrium properties such as the Potential of Mean Force (PMF). Of course, one would like to use all types of force fields (FF) ranging from classical ones to more advanced polarizable models using point induced dipoles and distributed multipoles such as AMOEBA. To enable such studies, the SMD methodology has been implemented in the framework of the massively parallel Tinker-HP software allowing for both long polarizable and non-polarizable MD simulations of large proteins. To validate this new implementation, we first compared the Tinker-HP SMD results to the literature. Tests have been performed on three different benchmark systems: the M–A deca-alanine (112 atoms), the ubiquitin (9737 atoms), and the CD2CD58 complex (97594 atoms). Non-polarizable (AMBER99, AMBER99SB, CHARMM22/CMAP, and OPLS–AA/L) and polarizable (AMOEBAPRO13 and AMOEBABIO18) force fields have been used. For each one of them, PMFs have been reconstructed and compared in terms of free energy barrier and hydrogen bonding fluctuations behavior over time. Using a SMD velocity of 0.01 Å/ps applied to a set of 20 trajectories, we show that polarizable and non-polarizable force fields do not always agree. As it could be anticipated, strong discrepancies are noticed between polarizable and non-polarizable models when considered in vacuum, whereas results are more comparable when a water environment is added. However, for the largest system, i.e., the CD2CD58 complex, strong differences related to the modeling of a salt bridge are noticed exhibiting some potential issues with classical FFs. Overall, such simulations highlight the importance of the inclusion of polarization effects as PMF free energy barriers computed with AMOEBA always decrease compared to non-polarizable force fields.
    Mots-clés : MACO, POLE 1.
    Pièce jointe Full Text PDF 3.9 Mo (source)


  • X. Frogneux, L. Hippolyte, D. Mercier, D. Portehault, C. Chanéac, C. Sanchez, P. Marcus, F. Ribot, L. Fensterbank, et S. Carenco, « Direct Synthesis of N-Heterocyclic Carbene-Stabilized Copper Nanoparticles from an N-Heterocyclic Carbene–Borane », Chemistry – A European Journal, vol. 25, nᵒ 49, p. 11481-11485, 2019.
    Résumé : N-Heterocyclic carbene (NHC)-stabilized copper nanoparticles (NPs) were synthesized from an NHC–borane adduct and mesitylcopper(I) under thermal conditions (refluxing toluene for 2.5 h). NPs with a size distribution of 11.6±1.8 nm were obtained. The interaction between Cu NPs and NHC ligands was probed by X-ray photoelectron spectroscopy, which showed covalent binding of the NHC to the surface of the NPs. Mechanistic studies suggested that NHC–borane plays two roles: contributing to the reduction of [CuMes]2 to release Cu0 species and providing NHC ligands to stabilize the copper NPs.
    Mots-clés : carbene ligands, copper, MACO, nanoparticles, POLE 1, radical reactions, reaction mechanisms.
    Pièce jointe Full Text PDF 853.3 ko (source)


  • « 15 Silicates in Photocatalysis », in Photocatalysis in Organic Synthesis, 2019ᵉ éd., B. König, Éd. Stuttgart: Georg Thieme Verlag, 2019.
    Mots-clés : CHEMBIO, MACO, POLE 1, POLE 3.


  • L. Lempenauer, G. Lemière, et E. Duñach, « Cyclisation Reactions Involving Alkyl Enol Ethers », Advanced Synthesis & Catalysis, 2019.
    Résumé : Enol ethers are a fascinating product class and valuable building blocks with versatile reactivities and synthetic applications. With the emergence of silyl enol ethers, the chemistry of simple alkyl enol ethers has received less attention and targeted reviews of their chemistry are scarce. Especially intramolecular reactions under participation of an enol ether function have never been specifically surveyed. The construction of cyclic scaffolds is arguably one of the most important and challenging tasks of the organic chemist and intramolecular cyclisations represent the most straight-forward tool to achieve this goal. The potential of enol ether-containing substrates to form oxygenated carbo- and heterocycles is obvious. The purpose of this review is to discuss their particular reactivity and to direct the reader's attention to how their unique properties have been harnessed by organic chemists for the construction of rings.
    Mots-clés : catalysis, cyclisations, enol ethers, intramolecular reactions, Lewis acids, MACO, POLE 1.
    Pièce jointe Full Text PDF 983.3 ko (source)


  • E. Levernier, V. Corcé, L. - M. Rakotoarison, A. Smith, M. Zhang, S. Ognier, M. Tatoulian, C. Ollivier, et L. Fensterbank, « Cross coupling of alkylsilicates with acyl chlorides via photoredox/nickel dual catalysis: a new synthesis method for ketones », Organic Chemistry Frontiers, vol. 6, nᵒ 9, p. 1378-1382, 2019.
    Résumé : Photoredox/nickel dual catalysis using easily oxidized bis-catecholato hypercoordinated silicon derivatives as radical sources and acyl chlorides as electrophiles allows a new method of formation of dialkyl and alkyl-aryl ketones as well as dibenzyl ketones which are less easily accessed. Flow chemistry can be used.
    Mots-clés : CHEMBIO, MACO, POLE 1, POLE 3.


  • C. Medena, F. Calogero, Q. Lemoine, C. Aubert, E. Derat, L. Fensterbank, G. Gontard, O. Khaled, N. Vanthuyne, J. Moussa, C. Ollivier, M. Petit, et M. Barbazanges, « A HELIXOL-Derived Bisphosphinite Ligand: Synthesis and Application in Gold-Catalyzed Enynes Cycloisomerization », European Journal of Organic Chemistry, vol. 2019, nᵒ 11, p. 2129-2137, 2019.
    Résumé : The synthesis, optical resolution through derivatization, characterization, and utilization of a new helical bis(phosphinite gold) complex derived from HELIXOL are described. By using an efficient cobalt catalyst, neither irradiation nor high catalytic loading was required to access the helicene of interest. The latter was phosphorylated to afford a new chiral ligand that was studied. Especially, treatment with AuCl(SMe2) gives a dinuclear gold complex that was used in cycloisomerization reactions.
    Mots-clés : ARC, Chirality, Enyne Cycloisomerization, Helicene, Homogeneous catalysis, MACO, Phosphinite, POLE 1.
    Pièce jointe Full Text PDF 1.5 Mo (source)


  • F. Medici, J. Maury, G. Lemière, et L. Fensterbank, « Interaction between Spirosilanes and Lewis Bases: from Coordination to Frustration », Chemistry – A European Journal, vol. 25, nᵒ 40, p. 9438-9442, 2019.
    Résumé : In this work, the interaction between Lewis bases, especially N-heterocyclic carbenes (NHCs), and hindered neutral silicon derivatives featuring high Lewis acidity is described. The formation of normal and abnormal Lewis adducts could be controlled by varying the acidity of the corresponding tetravalent spiro organosilane. Some DFT calculations permitted to gain insight into the thermodynamics of the NHC–spirosilane interaction featuring various NHCs differing in size and σ-donor capacity. Spirosilanes are introduced as new Lewis partners in frustrated Lewis pair (FLP) chemistry and some FLP-type reactivities are presented, in particular the activation of formaldehyde that could occur with both hindered NHCs and phosphines.
    Mots-clés : frustrated Lewis pairs, Lewis acid, MACO, pentavalent silic

    on, spirosilanes.


  • A. Vivien, M. Guillaumont, L. Meziane, C. Salzemann, C. Aubert, S. Halbert, H. Gérard, M. Petit, et C. Petit, « Role of Oleylamine Revisited: An Original Disproportionation Route to Monodispersed Cobalt and Nickel Nanocrystals », Chemistry of Materials, vol. 31, nᵒ 3, p. 960-968, févr. 2019.
    Résumé : Herein is highlighted an original disproportionation mechanism for the formation of hexagonal closed packed cobalt nanoparticles starting from low-valent cobalt complexes. By coupling experimental and theoretical studies, we demonstrate that oleylamine promotes the disproportionation of the starting metal complexes and controls the growth of the nanocrystals, in contrast to the role of reducing reagents proposed elsewhere. We also decipher the sensitivity of the synthesis in regard to the nature of the phosphine and of the halogen ligands in the starting cobalt precursors. Understanding of the mechanism allows the development of a less expensive and less toxic synthesis of these nanoparticles by decreasing the amount of oleylamine in alkane solvents. Finally, an extension of this process is presented and allows reaching size- and shape-controlled nanosphere and nanorod nickel nanoparticles.
    Mots-clés : MACO, POLE 1.


  • Z. Xia, V. Corcé, F. Zhao, C. Przybylski, A. Espagne, L. Jullien, T. Le Saux, Y. Gimbert, H. Dossmann, V. Mouriès-Mansuy, C. Ollivier, et L. Fensterbank, « Photosensitized oxidative addition to gold(i) enables alkynylative cyclization of o-alkylnylphenols with iodoalkynes », Nature Chemistry, vol. 11, nᵒ 9, p. 797-805, sept. 2019.
    Résumé : The well-established oxidative addition–reductive elimination pathway is the most followed one in transition metal-catalysed cross-coupling reactions. While readily occurring with a series of transition metals, gold(i) complexes have shown some reluctance to undergo oxidative addition unless special sets of ligands on gold(i), reagents or reaction conditions are used. Here we show that under visible-light irradiation, an iridium photocatalyst triggers—via triplet sensitization—the oxidative addition of an alkynyl iodide onto a vinylgold(i) intermediate to deliver C(sp)2–C(sp) coupling products after reductive elimination. Mechanistic and modelling studies support that an energy-transfer event takes place, rather than a redox pathway. This particular mode of activation in gold homogenous catalysis was applied in several dual catalytic processes. Alkynylbenzofuran derivatives were obtained from o-alkynylphenols and iodoalkynes in the presence of catalytic gold(i) and iridium(iii) complexes under blue light-emitting diode irradiation.
    Mots-clés : CHEMBIO, CSOB, MACO, POLE 1, POLE 3.

2018



  • M. Barbazanges et L. Fensterbank, « The Invention of New Methodologies: An Opportunity for Dating Natural Products », Synlett, août 2018.
    Résumé : This Account surveys almost two decades of methodological developments and their straightforward applications to the total synthesis of simple natural products. The main directions covered include radical chemistry and cascades, electrophilic catalysis based on coinage metals, and asymmetric synthesis based on bis(sulfoxides) auxiliaries. 1 Introduction 2 Radical Cascades 2.1 N-Cyanamides 2.2 Homolytic Substitution at Sulfur Atom to Give Sultines 3 Electrophilic Catalysis Based on Platinum(II) and Gold(I) Complexes 4 From Alkylydene Bis(sulfoxides) to Chiral Carboxylic Acids 5 Conclusion and Perspectives
    Mots-clés : asymmetric synthesis, bis(sulfoxides), gold catalysis, Key words radical chemistry, MACO, natural products, POLE 1, total synthesis.
    Pièce jointe Full Text PDF 450.4 ko (source)


  • L. Fensterbank, S. Gao, et A. Zakarian, « Themed collection: Synthetic approaches to natural products via catalytic processes », Organic Chemistry Frontiers, vol. 5, nᵒ 4, p. 529-530, févr. 2018.
    Résumé : A graphical abstract is available for this content
    Mots-clés : MACO, POLE 1.
    Pièce jointe Full Text PDF 481 ko (source)


  • L. Fensterbank, J. - P. Goddard, et C. Ollivier, « Visible-Light-Mediated Free Radical Synthesis », in Visible Light Photocatalysis in Organic Chemistry, Wiley-Blackwell, 2018, p. 25-71.
    Résumé : This chapter concentrates on the photocatalytic generation of radical intermediates that have already been encountered in the past and generated through other pathways. It particularly emphasizes how photocatalysis can really improve the reaction conditions and outcomes. Different oxygenated moieties can be introduced by photocatalysis in place of an initial C—H bond. The development of visible-light photoredox catalysis for radical synthesis has demonstrated high efficiency, selectivity, versatility, and functional group tolerance in various transformations, becoming of great interest in cascade processes intramolecular radical steps. One of the most developed cascade sequence is tandem intermolecular radical addition/homolytic aromatic substitution, which first comprises radical addition onto activated double bond followed by cyclization onto arene and rearomatization by subsequent oxidation of the radical adduct. Radical multicomponent processes have emerged as a convenient and flexible strategy to elaborate complex molecular building blocks. Among them, visible-light photoredox catalysis proved to be efficient for promoting radical/cationic multicomponent reactions (MCRS).
    Mots-clés : cationic multicomponent reaction, C—C bond formation, C—X bond formation, MACO, photocatalytic cycle, POLE 1, radical cascade applications, radical intermediates, radical multicomponent reaction, visible-light-mediated free radical synthesis.


  • F. Forato, A. Belhboub, J. Monot, M. Petit, R. Benoit, V. Sarou‐Kanian, F. Fayon, D. Jacquemin, C. Queffelec, et B. Bujoli, « Phosphonate-Mediated Immobilization of Rhodium/Bipyridine Hydrogenation Catalysts », Chemistry – A European Journal, vol. 24, nᵒ 10, p. 2457-2465, févr. 2018.
    Résumé : RhL2 complexes of phosphonate-derivatized 2,2′-bipyridine (bpy) ligands L were immobilized on titanium oxide particles generated in situ. Depending on the structure of the bipy ligand—number of tethers (1 or 2) to which the phosphonate end groups are attached and their location on the 2,2′-bipyridine backbone (4,4′-, 5,5′-, or 6,6′-positions)—the resulting supported catalysts showed comparable chemoselectivity but different kinetics for the hydrogenation of 6-methyl-5-hepten-2-one under hydrogen pressure. Characterization of the six supported catalysts suggested that the intrinsic geometry of each of the phosphonate-derivatized 2,2′-bipyridines leads to supported catalysts with different microstructures and different arrangements of the RhL2 species at the surface of the solid, which thereby affect their reactivity.
    Mots-clés : hydrogenation, immobilization, MACO, N ligands, POLE 1, rhodium, supported catalysts.
    Pièce jointe Full Text PDF 1.1 Mo (source)


  • S. H. Kyne, M. Clémancey, G. Blondin, E. Derat, L. Fensterbank, A. Jutand, G. Lefèvre, et C. Ollivier, « Elucidating Dramatic Ligand Effects on SET Processes: Iron Hydride versus Iron Borohydride Catalyzed Reductive Radical Cyclization of Unsaturated Organic Halides », Organometallics, vol. 37, nᵒ 5, p. 761-771, mars 2018.
    Résumé : An iron(II) borohydride complex ([(η1-H3BH)FeCl(NCCH3)4]) is employed as the precatalyst in iron-catalyzed radical cyclizations of unsaturated organic halides in the presence of NaBH4. Mechanistic investigations have established that the ligand bound to the metal center (acetonitrile versus ethylenebis(diphenylphosphine) (dppe)) plays a crucial role in the structure and reactivity of the active anionic iron(I) hydride ([HFeCl(dppe)2]−) and borohydride ([(η1-H3BH)FeCl(NCCH3)4]−) with unsaturated haloacetals. This work provides new insights into iron(I) hydride and borohydride species and their potential implication in single-electron processes.
    Mots-clés : MACO, POLE 1.


  • L. Lempenauer, A. Soupart, E. Duñach, et G. Lemière, « Synthesis of α-oxygenated β,γ-unsaturated ketones by a catalytic rearrangement strategy », Organic & Biomolecular Chemistry, vol. 16, nᵒ 30, p. 5441-5445, août 2018.
    Résumé : A straightforward two-step entry to α-oxgenated β,γ-unsaturated ketones from readily available α,β-unsaturated ketones is disclosed. It was found that bis(allylic) alcohols undergo a skeletal rearrangement in the presence of 1 mol% of cheap and non-corrosive p-toluenesulfonic acid. Computational studies were conducted to support the mechanism and to rationalise the influence of the catalyst acidity on the product selectivity.
    Mots-clés : MACO, POLE 1.
    Pièce jointe Full Text PDF 807.7 ko (source)


  • F. Medici, G. Gontard, E. Derat, G. Lemière, et L. Fensterbank, « Synthesis of Stable Pentacoordinate Silicon(IV)–NHC Adducts: An Entry to Anionic N-Heterocyclic Carbene Ligands », Organometallics, vol. 37, nᵒ 4, p. 517-520, févr. 2018.
    Résumé : This work features the previously undescribed interactions of Martin’s spirosilane with different types of N-heterocyclic carbenes (NHCs). The level of interaction proved to be strongly dependent on the size of the Lewis base and could vary from the formation of isolable classical Lewis adducts to abnormal Lewis adducts, as evidenced by X-ray diffraction structure analyses and NMR studies. It has been found that abnormal adducts could be used as precursors for the synthesis of anionic NHCs bearing a weakly coordinating siliconate component. Complexation of these new types of carbenes with gold(I) and copper(I) has been efficiently accomplished. DFT calculations performed on the siliconate-based anionic NHC ligands revealed a high-lying HOMO and therefore a strong σ-donor character.
    Mots-clés : MACO, POLE 1.


  • V. Mouriès-Mansuy et L. Fensterbank, « Gold-Catalyzed Migration of Propargyl Acetate as an Entry into the Total Synthesis of Natural Products », Israel Journal of Chemistry, vol. 58, nᵒ 5, p. 586-595, avr. 2018.
    Résumé : Abstract Gold catalysis has emerged over the last two decades as a protocole of choice for the efficient and selective activation of a variety of organic functional groups. This has served to the total synthesis of natural products at several occasions. In this context, the gold-catalyzed migration (1,2- or 1,3-) of propargyl acetates has been particularly used. This review highlights these different synthetic developments which are presented according to the involved mechanisms.
    Mots-clés : acetate migration, gold catalysis, MACO, organogold intermediate, POLE 1, propargyl acetate, total synthesis.
    Pièce jointe Full Text PDF 4.6 Mo (source)


  • Y. Ren, K. Cheaib, J. Jacquet, H. Vezin, L. Fensterbank, M. Orio, S. Blanchard, et M. Desage‐El Murr, « Copper-Catalyzed Aziridination with Redox-Active Ligands: Molecular Spin Catalysis », Chemistry – A European Journal, vol. 24, nᵒ 20, p. 5086-5090, avr. 2018.
    Résumé : Small-molecule catalysts as mimics of biological systems illustrate the chemists’ attempts at emulating the tantalizing abilities displayed by nature's metalloenzymes. Among these innate behaviors, spin multistate reactivity is used by biological systems as it offers thermodynamic leverage towards challenging chemical reactivity but this concept is difficult to translate into the realm of synthetic organometallic catalysis. Here, we report a rare example of molecular spin catalysis involving multistate reactivity in a small-molecule biomimetic copper catalyst applied to aziridination. This behavior is supported by spin state flexibility enabled by the redox-active ligand.
    Mots-clés : aziridination, copper catalysis, E-POM, MACO, multistate reactivity, POLE 1, POLE 2, redox-active ligands, spin catalysis.
    Pièce jointe Full Text PDF 963.4 ko (source)


  • J. Wengler, S. Ognier, M. Zhang, E. Levernier, C. Guyon, C. Ollivier, L. Fensterbank, et M. Tatoulian, « Microfluidic chips for plasma flow chemistry: application to controlled oxidative processes », Reaction Chemistry & Engineering, oct. 2018.
    Résumé : The present paper reports the integration of nonthermal plasma into a biphasic gas–liquid microfluidic chip. It evaluates the potential of plasma activation to become a synthetic tool in organic chemistry, operating under mild conditions (room temperature, atmospheric pressure) and without a catalyst. Few preceding works on plasma chemistry involved a liquid phase and none of them was able to handle the high reactivity of plasma to achieve both high conversion rates and selective reactions. We fabricated a glass-polymer microfluidic chip comprising a one metre long serpentine channel, in which a parallel gas–liquid flow was stabilized thanks to a specific step-like cross-sectional shape. Transparent ITO electrodes, deposited on both sides of the chip and linked to an AC high voltage source, produced a dielectric barrier discharge along the channel. We assessed the behaviour of the flow through optical observations and characterized the discharge through electrical measurements and real time intensified-CCD monitoring. We report the successful treatment of liquid cyclohexane with oxygen plasma inside our chip. The GC analysis of the outflowing liquid revealed only a partial oxidation of cyclohexane into a mixture of cyclohexanol and cyclohexanone (industrially known as “KA oil”), and cyclohexyl hydroperoxide, with a total selectivity above 70% and conversion up to 30%. This indicates that alkanes can be activated and functionalized by means of plasma discharges, in a controlled way. In that respect, we claim to have successfully overcome some of the barriers to industrially relevant plasma chemistry. We believe that the combined use of plasma and microfluidic technologies is essential to the development of this new field of research.
    Mots-clés : MACO, POLE 1.

2017


  • P. a Zhang, C. Tugny, J. Meijide Suárez, M. Guitet, E. Derat, N. Vanthuyne, Y. M. Zhang, O. Bistri, V. Mouries-Mansuy, M. Ménand, S. Roland, L. Fensterbank, et M. Sollogoub, « Artificial chiral metallo-pockets including a single metal serving as both structural probe and catalytic center », Chem, vol. 3, nᵒ 1, p. 174-191, 2017.
    Mots-clés : GOBS, MACO, POLE 1, POLE 3.


  • P. a Zhang, J. Meijide Suárez, T. Driant, E. Derat, Y. Zhang, M. Ménand, S. Roland, et M. Sollogoub, « Cyclodextrin Cavity-Induced Mechanistic Switch in Copper-Catalyzed Hydroboration », Angewandte Chemie International Edition, vol. 56, nᵒ 36, p. 10821-10825, août 2017.
    Mots-clés : catalysis, copper, cyclodextrins, GOBS, MACO, POLE 1, POLE 3, regioselectivity, supramolecular chemistry.
    Pièce jointe Full Text PDF 2.4 Mo (source)


  • M. Desage‐El Murr, L. Fensterbank, et C. Ollivier, « Iron and Single Electron Transfer: All is in the Ligand », Israel Journal of Chemistry, vol. 57, nᵒ 12, p. 1160-1169, déc. 2017.
    Résumé : This account describes some advances we have made in the field of iron catalysis. Two types of reactivity have been uncovered. Based on the use of an iron(II) precatalyst in the presence of NaBH4, the first one consists in a SET which can be useful for the reductive dehalogenation of iodide and bromide derivatives. Switching to the non-innocent bis-iminopyridine ligands promotes a previously undescribed Csp2−H activation reaction leading to biaryl derivatives. First clues into the intricate nature of the mechanism were obtained and suggested that the redox-active bis-iminopyridine ligand acts as an electron reservoir. The resulting buildup of electron density triggers the C−H bond breaking. All these findings are discussed in light of the existing literature and perspectives are given.
    Mots-clés : C−H Activation, C−X Activation, Iron Hydride, MACO, Redox Ligand, Single Electron Transfer.
    Pièce jointe Full Text PDF 3.8 Mo (source)


  • 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.


  • S. Guélen, M. Blazejak, L. - M. Chamoreau, A. Huguet, S. Derenne, F. Volatron, V. Mouriès-Mansuy, et L. Fensterbank, « Photochemical studies on bis-sulfide and -sulfone tethered polyenic derivatives », Organic & Biomolecular Chemistry, vol. 15, nᵒ 19, p. 4180-4190, mai 2017.
    Résumé : This study focusses on the [2 + 2]-photocycloaddition of a symmetric polyenic system tethered by an aryl bis-sulfide or sulfone platform. Using direct irradiation or photosensitization, no expected ladderane product was isolated. In most cases, only tricyclic products including a single cyclobutane moiety were formed. Irradiation of bis-acrylic precursors in water with encapsulation by a host (cyclodextrin or cucurbituril) provided a stereoselective access to valuable cyclobutyl adducts.
    Mots-clés : MACO, POLE 1.
    Pièce jointe Full Text PDF 1002.8 ko (source)


  • J. Jacquet, K. Cheaib, Y. Ren, H. Vezin, M. Orio, S. Blanchard, L. Fensterbank, et M. Desage‐El Murr, « Circumventing Intrinsic Metal Reactivity: Radical Generation with Redox-Active Ligands », Chemistry – A European Journal, vol. 23, nᵒ 60, p. 15030-15034, oct. 2017.
    Résumé : Nickel complexes have gained sustained attention as efficient catalysts in cross-coupling reactions and co-catalysts in dual systems due to their ability to react with radical species. Central to this reactivity is nickel's propensity to shuttle through several accessible redox states from Ni0 to NiIV. Here, we report the catalytic generation of trifluoromethyl radicals from a nickel complex bearing redox-active iminosemiquinone ligands. This unprecedented reactivity is enabled through ligand-based oxidation performing electron transfer to an electrophilic CF3+ source while the nickel oxidation state is preserved. Additionally, extension of this reactivity to a copper complex bearing a single redox equivalent is reported, thus providing a unified reactivity scheme. These results open new pathways in radical chemistry with redox-active ligands.
    Mots-clés : CF3. radicals, E-POM, MACO, nickel, POLE 2, redox-active ligand, single electron transfer.
    Pièce jointe Full Text PDF 790 ko (source)


  • 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.


  • C. Ollivier et L. Fensterbank, « A Triple Catalysis for Alkyl-Alkyl Coupling: An Advance toward the Ideal Synthesis », Chem, vol. 3, nᵒ 2, p. 207-208, août 2017.


  • 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 calculatio

    ns 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.


  • C. Tugny, O. Khaled, E. Derat, J. - P. Goddard, V. Mouriès-Mansuy, et L. Fensterbank, « Gold(I)-catalyzed access to neomerane skeletons », Organic Chemistry Frontiers, vol. 4, nᵒ 10, p. 1906-1916, sept. 2017.
    Résumé : The gold(I) catalyzed cycloisomerization of an enynyl propargylic ester, featuring a 1,2-acyloxy migration/intramolecular cyclopropanation sequence, opens a straightforward access to the 5,7,3-tricyclic skeleton of neomerane sesquiterpenes. The first total synthesis of 5-epi-valeneomerin B in 12 steps with an overall yield of 5.3% from the readily available hex-5-en-2-one is reported.
    Mots-clés : MACO, POLE 1.


  • Y. Wang, A. Monfredini, P. - A. Deyris, F. Blanchard, E. Derat, G. Maestri, et M. Malacria, « All-metal aromatic cationic palladium triangles can mimic aromatic donor ligands with Lewis acidic cations », Chemical Science, vol. 8, nᵒ 11, p. 7394-7402, oct. 2017.
    Résumé : We present that cationic rings can act as donor ligands thanks to suitably delocalized metal–metal bonds. This could grant parent complexes with the peculiar properties of aromatic rings that are crafted with main group elements. We assembled Pd nuclei into equilateral mono-cationic triangles with unhindered faces. Like their main group element counterparts and despite their positive charge, these noble-metal rings form stable bonding interactions with other cations, such as positively charged silver atoms, to deliver the corresponding tetranuclear dicationic complexes. Through a mix of modeling and experimental techniques we propose that this bonding mode is an original coordination-like one rather than a 4-centre–2-electron bond, which have already been observed in three dimensional aromatics. The present results thus pave the way for the use of suitable metal rings as ligands.
    Mots-clés : MACO, POLE 1.
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2016

  • C. Aubert, L. Tortech, V. Gandon, D. Fichou, M. Malacria, et G. Bertrand, « Use of Cobalt Complexes for Preparing an Active Layer in a Photovoltaic Cell, and Corresponding Photovoltaic Cell. », U.S. Patent US Patent N°9,263,683.
    Mots-clés : MACO, NASCO, POLE 1, POLE 2.


  • 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, 2016.
    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 », Nanoscale, vol. 8, nᵒ 44, p. 18640-18645, nov. 2016.
    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.

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