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26 results on '"Schweizer, Stéphane"'

4. Stereodivergent Hydrosilylation, Hydrostannylation and Hydrogermylation of alpha-Trifluoromethylated Alkynes and their Synthetic Applications

Author

Tresse, Cédric, Schweizer, Stéphane, Bisseret, Philippe, Lalevée, Jacques, Evano, Gwilherm, Blanchard, Nicolas, Tresse, Cédric, Schweizer, Stéphane, Bisseret, Philippe, Lalevée, Jacques, Evano, Gwilherm, and Blanchard, Nicolas

Abstract

Stereoselective hydrometalation reactions of aryl- and alkyl substituted trifluoromethylated alkynes with triethylsilane, tributylstannane and triphenylgermane have been investigated. (E)-α-CF3-vinylsilanes, stannanes and germanes have been obtained under palladium-catalyzed conditions whereas the corresponding (Z)-α-CF3-vinylgermanes were obtained under radical conditions. These reactions proceed in good to excellent yields and possess a broad functional group tolerance. The applications of the (Z)- and (E)-α-CF3-vinylgermanes in palladium-catalyzed cross-coupling reactions with aryl halide having diverse electronic requirements was also investigated. The corresponding (Z)- and (E)-α-CF3- styrenes were obtained as single isomers, thus demonstrating the utility of these versatile synthons for the synthesis of stereodefined trifluoromethylated alkenes., info:eu-repo/semantics/published

Published
2016

6. Stereodivergent Hydrogermylations of α‑Trifluoromethylated Alkynes and Their Applications in Cross-Coupling Reactions

Author

Schweizer, Stéphane, Tresse, Cédric, Bisseret, Philippe, Lalevée, Jacques, Evano, Gwilherm, Blanchard, Nicolas, Schweizer, Stéphane, Tresse, Cédric, Bisseret, Philippe, Lalevée, Jacques, Evano, Gwilherm, and Blanchard, Nicolas

Abstract

The hydrometalation of alkynes with group 14 elements such as tin- or silyl hydrides is a classical transformation in organic synthesis. Strangely, among the group 14 elements, the use of germanium hydrides is rarely seen. Two efficient, stereodivergent, and broadly applicableroutes to (Z)- and (E)-α-CF3-vinylgermanes by regio- and stereoselective hydrogermylation of α-trifluoromethylated alkynes under radical or transition-metal-catalyzed conditions are reported. Furthermore, we demonstrate that the resulting stereodefined fluorinated building blocks are remarkable cross-coupling partners, provided that the vinylgermane is appropriately tuned electronically, as demonstrated by the synthesis of trisubstituted (Z)- and (E)-α-trifluoromethylated alkenes., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2015

10. Turning Unreactive Copper Acetylides into Remarkably Powerful and Mild Alkyne Transfer Reagents by Oxidative Umpolung

Author

Evano, Gwilherm, Jouvin, Kevin, Theunissen, Cédric, Guissart, Céline, Laouiti, Anouar, Tresse, Cédric, heimburger, Jérémy, Bouhoute, Yassine, Veillard, Romain, Lecomte, Morgan, Nitelet, Antoine, Schweizer, Stéphane, Blanchard, Nicolas, Alayrac, Carole, Gaumont, Annie-Claude, Evano, Gwilherm, Jouvin, Kevin, Theunissen, Cédric, Guissart, Céline, Laouiti, Anouar, Tresse, Cédric, heimburger, Jérémy, Bouhoute, Yassine, Veillard, Romain, Lecomte, Morgan, Nitelet, Antoine, Schweizer, Stéphane, Blanchard, Nicolas, Alayrac, Carole, and Gaumont, Annie-Claude

Abstract

This is not breaking news: copper acetylides, readily available polymeric rock-stable solids, have been known for more than a century to be unreactive species and piteous nucleophiles. This lack of reactivity actually makes them ideal alkyne transfer reagents that can be easily activated under mild oxidizing conditions. When treated with molecular oxygen in the presence of simple chelating nitrogen ligands such as TMEDA, phenanthroline or imidazole derivatives, they are smoothly oxidized to highly electrophilic species that formally behave like acetylenic carbocations and can therefore be used for the mild and practical alkynylation of a wide range of nitrogen, phosphorus and carbon nucleophiles., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2014

11. Practical Methods for the Synthesis of Trifluoromethylated Alkynes: Oxidative Trifluoromethylation of Copper Acetylides and Alkynes

Author

Tresse, Cédric, Guissart, Céline, Schweizer, Stéphane, Bouhoute, Yassine, Chany, Anne-Caroline, Goddard, Mary-Lorène, Blanchard, Nicolas, Evano, Gwilherm, Tresse, Cédric, Guissart, Céline, Schweizer, Stéphane, Bouhoute, Yassine, Chany, Anne-Caroline, Goddard, Mary-Lorène, Blanchard, Nicolas, and Evano, Gwilherm

Abstract

Two practical and complementary methods are reported for the synthesis of trifluoromethylated alkynes. The first one, a mix-and-stir process, is based on the oxidative trifluoromethylation of readily available and bench-stable copper acetylides while the second one, which displays a broad substrate scope and has several advantages over existing procedures, is based on the oxidative copper- catalyzed direct trifluoromethylation of terminal alkynes. Both reactions provide user-friendly processes for the synthesis of trifluoromethylated acetylenes which can be easily obtained from readily available starting materials., SCOPUS: ar.j, FLWNA, info:eu-repo/semantics/published

Published
2014

13. On the Synthesis, Characterization and Reactivity of N‐Heteroaryl–Boryl Radicals, a New Radical Class Based on Five‐Membered Ring Ligands

Author

Tehfe, Mohamad‐Ali, primary, Schweizer, Stéphane, additional, Chany, Anne‐Caroline, additional, Ysacco, Cédric, additional, Clément, Jean‐Louis, additional, Gigmes, Didier, additional, Morlet‐Savary, Fabrice, additional, Fouassier, Jean‐Pierre, additional, Neuburger, Markus, additional, Tschamber, Théophile, additional, Blanchard, Nicolas, additional, and Lalevée, Jacques, additional

Published
2014
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14. Formation of N-Heterocyclic Carbene–Boryl Radicals through Electrochemical and Photochemical Cleavage of the B–S bond in N-Heterocyclic Carbene–Boryl Sulfides

Author

Telitel, Sofia, primary, Vallet, Anne-Laure, additional, Schweizer, Stéphane, additional, Delpech, Bernard, additional, Blanchard, Nicolas, additional, Morlet-Savary, Fabrice, additional, Graff, Bernadette, additional, Curran, Dennis P., additional, Robert, Marc, additional, Lacôte, Emmanuel, additional, and Lalevée, Jacques, additional

Published
2013
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15. Mechanistic and Preparative Studies of Radical Chain Homolytic Substitution Reactions of N-Heterocyclic Carbene Boranes and Disulfides

Author

Pan, Xiangcheng, primary, Vallet, Anne-Laure, additional, Schweizer, Stéphane, additional, Dahbi, Karim, additional, Delpech, Bernard, additional, Blanchard, Nicolas, additional, Graff, Bernadette, additional, Geib, Steven J., additional, Curran, Dennis P., additional, Lalevée, Jacques, additional, and Lacôte, Emmanuel, additional

Published
2013
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22. Stereodivergent Hydrogermylations of α-TrifluoromethylatedAlkynes and Their Applications in Cross-Coupling Reactions.

Author

Schweizer, Stéphane, Tresse, Cédric, Bisseret, Philippe, Lalevée, Jacques, Evano, Gwilherm, and Blanchard, Nicolas

Subjects
*STEREOCHEMISTRY, *METHYLATION, *ALKYNES, *COUPLING reactions (Chemistry), *ORGANIC synthesis, *HYDRIDES
Abstract

The hydrometalation of alkynes withgroup 14 elements such as tin- or silyl hydrides is a classical transformationin organic synthesis. Strangely, among the group 14 elements, theuse of germanium hydrides is rarely seen. Two efficient, stereodivergent,and broadly applicable routes to (Z)- and (E)-α-CF3-vinylgermanes by regio- and stereoselectivehydrogermylation of α-trifluoromethylated alkynes under radicalor transition-metal-catalyzed conditions are reported. Furthermore,we demonstrate that the resulting stereodefined fluorinated buildingblocks are remarkable cross-coupling partners, provided that the vinylgermaneis appropriately tuned electronically, as demonstrated by the synthesisof trisubstituted (Z)- and (E)-α-trifluoromethylatedalkenes. [ABSTRACT FROM AUTHOR]

Published
2015
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24. Soft PhotopolymerizationsInitiated by Dye-SensitizedFormation of NHC-Boryl Radicals under Visible Light.

Author

Telitel, Sofia, Schweizer, Stéphane, Morlet-Savary, Fabrice, Graff, Bernadette, Tschamber, Théophile, Blanchard, Nicolas, Fouassier, Jean Pierre, Lelli, Moreno, Lacôte, Emmanuel, and Lalevée, Jacques

Subjects
*PHOTOPOLYMERIZATION, *DYE-sensitized solar cells, *CARBENES, *HETEROCYCLIC compounds, *RADICALS (Chemistry), *ACRIDINE
Abstract

A procedure for the production of N-heterocyclic carbene–borylradicals (NHC-BH2•) upon visible lightirradiation under soft conditions is presented. New acridine orange(dye)/diphenyl disulfide/NHC–BH3and dye/sulfoniumsalt/NHC–BH3three-component initiating systemsare introduced for the efficient visible light photopolymerizationof trimethylolpropane triacrylate. The new systems could be extendendto polymerization reactions in water (hydroxyethyl acrylate and hydroxyethylmethyl acrylate), which proceeded with strongly improved polydispersity.The chemical mechanisms are investigated through EPR and photolysisexperiments. [ABSTRACT FROM AUTHOR]

Published
2013
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25. On the synthesis, characterization and reactivity of N-heteroaryl-boryl radicals, a new radical class based on five-membered ring ligands.

Author

Tehfe MA, Schweizer S, Chany AC, Ysacco C, Clément JL, Gigmes D, Morlet-Savary F, Fouassier JP, Neuburger M, Tschamber T, Blanchard N, and Lalevée J

Abstract

The synthesis and physical characterization of a new class of N-heterocycle-boryl radicals is presented, based on five membered ring ligands with a N(sp(2) ) complexation site. These pyrazole-boranes and pyrazaboles exhibit a low bond dissociation energy (BDE; BH) and accordingly excellent hydrogen transfer properties. Most importantly, a high modulation of the BDE(BH) by the fine tuning of the N-heterocyclic ligand was obtained in this series and could be correlated with the spin density on the boron atom of the corresponding radical. The reactivity of the latter for small molecule chemistry has been studied through the determination of several reaction rate constants corresponding to addition to alkenes and alkynes, addition to O2 , oxidation by iodonium salts and halogen abstraction from alkyl halides. Two selected applications of N-heterocycle-boryl radicals are also proposed herein, for radical polymerization and for radical dehalogenation reactions., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2014
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26. Highly efficient and reusable supported pd catalysts for Suzuki-Miyaura reactions of aryl chlorides.

Author

Schweizer S, Becht JM, and Le Drian C

Abstract

Syntheses of air- and moisture-stable heterogeneous (tert-butylarylphosphino)polystyrene-supported Pd catalysts and their use for versatile Suzuki-Miyaura reactions of aryl chlorides and arylboronic acids under non-anhydrous conditions are reported. The catalysts are easily recovered by filtration. They can be used many times (more than seven) without showing any loss of activity, and the amount of Pd leached is extremely low (<0.1%).

Published
2007
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