Préparation de liquides ioniques chiraux (quelques exemples d'applications en synthèse asymétrique)

A cours de ce travail, nous avons mis au point, dans un premier temps, une méthode de synthèse propre et efficace de liquides ioniques, dans des conditions de chimie verte', sous irradiation des micro-ondes et en absence de solvant. Grâce à cette méthode facile à mettre en œuvre, différentes familles de liquides ioniques, basées sur les cations imidazolium et pyridinium ont été synthétisées de manière rapide (23- 30 minutes) avec de très bons rendements (86-99%).Des effets spécifiques des micro-ondes ont été mis en évidence. Des calculs de chimie quantique ont été effectués et nous ont permis de confirmer l'existence de ces effets spécifiques sur des réactions modèle.Par la même methode une famille de liquides ioniques chiraux, basés sur les sels d'éphédrinium a été synthétisée avec de bons rendements (77 91%) en temps très courts (10- 180 minutes) Nous avons, par la suite, étudié le rôle des ioniques chiraux en synthèse et catalyse asymétrique. Ainsi nous avons décrit, pour la première fois, que les liquides ioniques chiraux, basés sur les sels d'éphédrinium, peuvent être utilisés comme nouveaux milieux réactionnels chiraux dans la réaction de Baylis-Hillman asymétrique. Des résultats significatifs en terme d'énantiosélectivité (ee< 44%) ont été obtenus via un transfert de chiralité grâce à l'utilisation de ces nouveaux milieux chiraux.Nous avons également montré que ces liquides ioniques peuvent remplacer les catalyseurs acides de Lewis chiraux et les solvants organiques conventionnels dans la réaction d'aza Diels-Alder entre une imine et le diène de Danishefsky. De bons rendements (66- 77%) ainsi qu'une diastéréosélectivité allant jusqu'66% ont été obtenus.During my Ph.D thesis we have developed an efficient method for the synthesis of ionic liquids under green chemistry conditions, using microwave activation without any organic solvent. By this method, different ionic liquids families, based on imidazolium or pyridinium cation, have been synthesized quickly (23-30 min) and easily in good yield (86-99%).A comparative studies of reactivity between microwave activation and conventional heating have been made. Non thermal microwave specific effects were evident. These results have been quantitatively determined by theorical calculationIn view of emerging importance of ionic liquids as new reaction media for organic syntheses especially in asymmetric synthesis, we prepared, by the same way chiral ionic liquide based on (1R, 2S)-ephedrinium salt in good yields (77-91%) within very short reaction times (10-180 min).We had alsostudied the role of chiral ionic liquids in asymmetric synthesis and catalysis. For this purpose we repoted for the first time, the use of chiral ionic liquids as reaction media in asymmetric Baylis-Hillman reaction. Significant results (ee< 44%) in term of enantioselectivity were obtained via chirality transfert from chiral ionic liquids.The aza-Diels-Alder reaction between Danishefsky's diene and imines was also studied in ionic liquids. The reaction has been found to perform better in ionic liquids using no acid catalyst at room temperature. Chiral ionic liquids are also used as new reaction media for reaction. Good yields (66- 77%) and more importantly, moderate diastereoselectivities up to 66% were obtained.Having established the all important role of ionic liquids in asymmetric transformation.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Designing functional polyoxometalate-based ionic liquid crystals and ionic liquids

International audiencePolyoxometalate (POM) compounds constitute a wide family rich of more than several thousand inorganic compounds which can be finely tuned at the molecular level. Considering their high diversities in structures and properties, the incorporation of such inorganic components into liquid crystalline phases or ionic liquid phases is particularly relevant for the elaboration of functional materials. By adjusting the molecular structures of the anions and the nature of the counter cations, many authors designed different types of mesophases sometimes with application in optoelectronics, or true POM-based Ionic liquids (POM-ILs with melting temperature below 100 °C). The latter turn out to be highly interesting for various applications in catalysis, depollution, or protection of the historical heritage. This review focuses on the recent developments in these organic/inorganic hybrid materials, POMbased Ionic liquid crystal and POM-ILs and their applications

General, Practical and Selective Oxidation Protocol for CF3S into CF3S(O) Group

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Synthesis of N-Alkenyl and N-Alkynyl S-Perfluoroalkylated Sulfoximines by Copper Catalysis

International audienceThe introduction of a double or triple bond to the nitrogen atom of S-perfluoroalkyl sulfoximines is described. We propose a simple catalytic system based on copper iodide for the reaction with bromoalkenes and bromoalkynes, and based on copper dichloride for the coupling with terminal alkynes. The fluorinated chain was varied from perfluorobutyl to monofluoromethyl. The reaction proceeds efficiently when the unsaturated system is substituted by an aryl or alkyl group. In particular, aliphatic terminal alkynes are efficient substrates for this transformation

Biodegradable, non-bactericidal oxygen-functionalised imidazolium esters: A step towards ‘greener’ ionic liquids

9 pages, 6 figures, tables.A series of imidazolium ionic liquids was prepared and screened against 7 bacterial strains. The incorporation of ether groups into the ester side-chain significantly reduced the toxicity compared with alkyl ester derivatives. Biodegradation data are also presented for 15 of the ionic liquids—including 6 examples which can be classed as readily biodegradable.Enterprise Ireland (NG, SM, BP) and the EPA 2006-PHDET- 7 studentship (NG, DC) are gratefully acknowledged for their financial support. We also thank Dr Orla Cahill for her assistance of DF.Peer reviewe

(Trifluoromethylselenyl)methylchalcogenyl as emerging fluorinated groups: synthesis under photoredox catalysis and determination of the lipophilicity

International audienceThe synthesis of molecules bearing (trifluoromethylselenyl)methylchalcogenyl groups is described via an efficient two-step strategy based on a metal-free photoredox catalyzed decarboxylative trifluoromethylselenolation with good yields up to 88% which raised to 98% in flow chemistry conditions. The flow methods allowed also to scale up the reaction. The mechanism of this key reaction was studied. The physico-chemical characterization of these emerging groups was performed by determining their Hansch-Leo lipophilicity parameters with high values up to 2.24. This reaction was also extended to perfluoroalkylselenolation with yields up to 95%. Finally, this method was successfully applied to the functionalization of relevant bioactive molecules such as tocopherol or estrone derivatives

Fe-mediated nucleophilic trifluoromethylselenolation of activated alkyl bromides via umpolung reactivity of trifluoromethyl tolueneselenosulfinate

International audienceTrifluoromethyl tolueneselenosulfonate is a versatile reagent which can be reduced by iron powder to generate in situ trifluoromethylselenolate anion. This species can then react with alkyl bromide to perform SN2 reaction

Fluoroalkyl Amino Reagents for the Introduction of the Fluoro(trifluoromethoxy)methyl Group onto Arenes and Heterocycles

International audienceFluoroalkyl amino reagents 1a and 2a have been developed from commercially available trifluoromethyl trifluorovinyl ether via a hydroamination reaction with diethylamine or dimethylamine. These reagents can be activated by treatment with a Lewis acid and subsequently used as a mono- or dielectrophile for the introduction of the fluoro(trifluoromethoxy)methyl group, either in Vilsmeier-type acylations of aromatic substrates or in the synthesis of fluorinated pyrazoles from CH-acidic substrates and of bis-fluorinated pyrazoles, all being important building blocks for medicinal and agricultural chemistry

Vinylic Trifluoromethylselenolation via Pd‐Catalyzed C−H Activation

International audienceTrifluorometylselenolation via C−H activation is barely described in literature. In particular, no such vinylic functionalization has been yet described. Herein, a palladium-catalyzed trifluoromethylselenolation of vinylic C−H bonds is described. The 5-methoxy-8-aminoquinoline has been used as auxiliary directing group to perform this reaction. The reaction gives excellent yields with α-substituted compounds whatever the substituents and a microwave activation can be used to accelerate the reaction. With β-substituted substrates lower yields, but still satisfactory, are obtained. This methodology was also successfully extended to other fluoroalkylselenyl groups

New and general access to S-perfluoroalkyl NH sulfoximines

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