Personne : Ollevier, Thierry
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Ollevier
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Thierry
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Université Laval. Département de chimie
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Publication Accès libre Asymmetric Fe II -Catalyzed Thia-Michael addition reaction to α,β-unsaturated Oxazolidin-2-one Derivatives(American Chemical Society, 2017-11-20) Ollevier, Thierry; Keipour, Hoda; Gandon, Vincent; Lauzon, SamuelA highly enantioselective FeII-catalyzed thia-Michael addition to α,β-unsaturated carbonyl derivatives was developed. The scope of the reaction was demonstrated with a selection of aromatic, heterocyclic and aliphatic thiols, and various Michael acceptors. The corresponding β-thioethers were obtained in good to excellent yields (up to 98%) and moderate to excellent enantioselectivities (up to 96:4 er). Unusual hepta-coordination of the metal and chelation to α,β-unsaturated oxazolidin-2-one derivatives allowed the construction of a coherent model rationalizing the enantioselective event. DFT calculations support the proposed model for observed stereoselectivities.Publication Accès libre Recyclable iron(II) caffeine-derived ionic salt catalyst in the Diels–Alder reaction of cyclopentadiene and α,β-unsaturated N-acyloxazolidinones in dimethyl carbonate(Royal Society of Chemistry, 2019-07-15) Ollevier, Thierry; Li, Dazhi; Meng, DiIron(II) triflate was used in combination with caffeine-derived salts as recyclable catalysts for the Diels–Alder reaction run in dimethyl carbonate (DMC) as a green solvent. The catalyst was prepared as an ionic salt from a xanthinium salt and Fe(OTf)2. Various substrates including α,β-unsaturated carbonyl and N-acyloxazolidinone derivatives were reacted with cyclopentadiene using this recyclable catalyst. The use of a low catalyst loading (1 mol%) afforded high yields (up to 99%) of the corresponding cycloadducts. The recycling and the efficiency of the catalyst were demonstrated for several runs.Publication Accès libre Fe(BF4)2 catalyzed inter- and intramolecular carbonyl-ene reaction of trifluoropyruvate(Georg Thieme Verlag Stuttgart, 2017-12-13) Ollevier, Thierry; Meng, DiInter- and intramolecular carbonyl-ene reactions have been developed using 5 mol% Fe(BF4)2 as catalyst, affording homoallylic alcohols in 36–87% isolated yields. This catalyst, prepared from FeCl2 and AgBF4, is the first FeII Lewis acid reported for the carbonyl-ene reaction using ethyl trifluoropyruvate. The method was successfully applied to the reaction of various 1,1-disubstituted alkenes with ethyl trifluoropyruvate and to the cyclization of citronellal.Publication Accès libre Asymmetric Cu1-Catalyzed Insertion Reaction of 1-Aryl-2,2,2- trifluoro-1-diazoethanes into Si–H Bonds(American Chemical Society, 2019-10-28) Ollevier, Thierry; Carreras, Virginie; Gandon, Vincent; Besnard, ClaireAn asymmetric copper(I)-catalyzed Si−H insertion reaction of 1-aryl-2,2,2-trifluoro-1-diazoethanes in dimethyl carbonate as a green solvent alternative was developed. A C2-symmetric copper(I) diimine complex enabled the asymmetric insertion reaction to give enantioenriched (1-aryl-2,2,2-trifluoroethyl)silanes with excellent stereoselectivities (up to 98:2 er). Successful conversion of the silanes into the corresponding alcohols was performed with retention of stereochemistry. Mechanistic studies and DFT calculations support the proposed model for the observed stereoselectivities.Publication Accès libre Hydrogen peroxide/dimethyl carbonate : a green system for epoxidation of N-alkylimines and N-sulfonylimines. One-pot synthesis of N-alkyloxaziridines from N-alkylamines and (hetero)aromatic aldehydes(Royal Society of Chemistry, 2016-07-25) Ollevier, Thierry; Ghedira, Donia; Kraïem, JamilA green method for epoxidation of imines using an environmentally benign oxidant system, H2O2/dimethyl carbonate, was developed. N-Alkyloxaziridines were prepared in high yields from N-alkylamines and (hetero)aromatic aldehydes in one-pot fashion, whereas N-sulfonyloxaziridines have been prepared by using the same oxidant system and 5 mol% of Zn(OAc)2·2H2O as catalyst.Publication Accès libre The power of iron catalysis in diazo chemistry(Thieme Medical Pub., 2020-09-15) Ollevier, Thierry; Carreras, Virginie; Tanbouza, NourThe use of iron catalysis to enable reactions with diazo compounds has emerged as a valuable tool to forge carbon–carbon or carbon–heteroatom bonds. While diazo compounds are often encountered with toxic and expensive metal catalysts, such as Rh, Ru, Pd, Ir, and Cu, a resurgence of Fe catalysis has been observed. This short review will showcase and highlight the recent advancements in iron-mediated reactions of diazo compounds.Publication Accès libre Iron-modified mesoporous silica as efficient solid lewis acid catalyst for the mukaiyama aldol reaction(American Chemical Society, 2018-01-08) Ollevier, Thierry; Kleitz, Freddy; Xu, WanFe-MCM-41 and Fe-SBA-15, two different iron-containing mesoporous silicas, were successfully synthesized by a straightforward and versatile method using iron acetylacetonate as a metal precursor. pH adjustment with ammonia during the synthesis was found to be an efficient way to improve the iron content. Physicochemical parameters of the iron-containing mesoporous silicas were obtained by nitrogen physisorption measurements, and the coordination environment of iron elements was validated by UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The surface acidity was tested by using a series of Hammett indicators. To further distinguish the Lewis acid sites on the surface, a pyridine adsorption FT-IR method was implemented. These prepared nanoporous catalysts were screened in the Mukaiyama aldol reaction as a model reaction catalyzed by a Lewis acid. The Lewis acid catalytic activity of the materials was fine-tuned, and the corresponding aldol products were obtained in good yield and selectivity. More importantly, the solid catalysts were very stable and could be reused at least nine times while maintaining the same catalytic activity.Publication Accès libre Fe(OTf)2-catalyzed thia-Michael addition reaction : a green synthetic approach to β-thioethers(Wiley, 2018-06-28) Ollevier, Thierry; Keipour, Hoda; Lauzon, Samuel; Li, MaoA convenient Fe(OTf)2‐catalyzed Michael addition reaction of thiols to α,β‐unsaturated carbonyl compounds was developed. The use of a simple procedure (EtOH, room temperature, air atmosphere) allowed to set up effective green catalytic conditions for the C‐S bond formation. The scope of the reaction was demonstrated using various substituted thiols and original Michael acceptors. The corresponding β‐thioethers were obtained in good to excellent yields (up to 99%). Also, the derivatization into the one‐pot thia‐Michael addition/oxidation reaction of 3‐(3‐(phenylthio)butanoyl)oxazolidin‐2‐one using H2O2 has proven to be efficient.Publication Accès libre Bridging lab and industry with flow electrochemistry(Cell Press, 2020-10-22) Ollevier, Thierry; Tanbouza, NourA revitalization of organic electrosynthesis has incited the organic chemistry community to adopt electrochemistry as a green and cost-efficient method for activating small molecules to replace highly toxic and expensive redox chemicals. However, many of the critical challenges of batch electrosynthesis, especially for organic synthesis, still remain. The combination of continuous flow technology and electrochemistry is a potent means to enable industry to implement large scale electrosynthesis. Indeed, flow electrosynthesis helps overcome problems that mainly arise from macro batch electro-organic systems, such as mass transfer, ohmic drop, and selectivity, but this is still far from being a flawless and generic applicable process. As a result, a notable increase in research on methodology and hardware sophistication has emerged, and many hitherto uncharted chemistries have been achieved. To better help the commercialization of wide-scale electrification of organic synthesis, we highlight in this perspective the advances made in large-scale flow electrosynthesis and its future trajectory while pointing out the main challenges and key improvements of current methodologies.Publication Accès libre Hydrogen bond-promoted metal-free hydroamination of alkynes(Thieme, 2019-10-07) Bahri, Janet; Ollevier, Thierry; Tanbouza, Nour; Taillefer, Marc; Monnier, FlorianAn original metal-free regio- and stereoselective intermolecular hydroamination of alkynes is described. Various (E)-enamines were obtained from arylacetylenes and aliphatic secondary amines in the presence of ethylene glycol as a solvent. The latter is assumed to play a major role in the mechanism through hydrogen bonding and proton exchange.