- Chalice-Type Tridentate Silicon Lewis Acids of C3 Symmetry in a Single Step Starting from Hexadehydrotribenzo[12]annulene
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Tridentate Lewis acids with aligned functions were synthesized based on the rigid framework hexadehydrotribenzo[12]annulene. The backbone and its fluorinated analogue were synthesised in one-pot syntheses, with alkyne deprotection and Sonogashira cross coupling reaction being carried out in one step. Hydrosilylation of the annulene with chlorohydrosilanes proceeded highly selectively and afforded rigid poly-Lewis acids with three SiCl3 or SiCl2Me substituents perfectly oriented to one side of the molecule in a single step. The progress of hydrosilylation was investigated by time-correlated NMR spectroscopic studies. The crystal structures show that the framework is symmetrically functionalised and the silyl substituents are aligned in one direction. To increase the acidity of the Lewis acids the chlorosilyl substituents were fluorinated with SbF3. Further investigation of hydrometallation reactions (M=B, Al, Ga, Sn) did not lead to corresponding structures.
- Schwartzen, Anna,Weddeling, Jan-Henrik,Langosch, Jana,Neumann, Beate,Stammler, Hans-Georg,Mitzel, Norbert W.
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supporting information
p. 1821 - 1828
(2020/12/25)
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- Halogenation reactions
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A method of halogenating an aromatic compound which comprises the steps of reacting an halogenating agent with the aromatic compound in the presence of fluorine and an acid, wherein the halogenating agent is at least one of an iodinating agent, a brominating agent and an chlorinating agent.
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- Reactions of polyfluoroaromatic compounds with electrophilic agents in the presence of tris(dialkylamino)phosphine: 6. * Reactions of halogenotetrafluorobenzenes RC6F4X (X = Cl, Br, or I) with chlorotrimethylsilane
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The rate of replacement of the halogen atom in isomers of RC6F4X (X = Cl, Br, or I) by the SiMe3 group under the action of Me3SiCl and P(NEt2)3 depends on the nature and the mutual arrangement of the substituents X and R. In addition to silyldehalogenation, compounds C6HF4X (X = Br or I) undergo silyldeprotonation and reduction to tetrafluorobenzenes.
- Bardin
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p. 780 - 785
(2007/10/03)
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- Elemental fluorine. Part 4. Use of elemental fluorine for the halogenation of aromatics
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New methodolgy for direct iodination of benzenoid compounds has been developed; the aromatic substrate is simply mixed with iodine and sulfuric acid, suspended in an inert medium, such as 1,1,2-trichlorotrifluoroethane (CF2ClCFCl2) or perfluorocarbon, and elemental fluorine is passed through the system at room temperature. High conversions to iodoaromatic products occur, even with some deactivated systems, e.g. nitrobenzene. A very powerful brominating system is produced using the analagous methodology.
- Chambers, Richard D.,Skinner, Christopher J.,Atherton, Malcolm J.,Moilliet, John S.
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p. 1659 - 1664
(2007/10/03)
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- Elemental Fluorine as an 'Enabler' for Generation of Powerful Electrophiles from Other Halogens
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A new direct iodination procedure for aromatic systems involves iodine, substrate, sulfuric acid, and elemental fluorine at room temperature.
- Chambers, Richard D.,Skinner, Christopher J.,Atherton, Malcolm,Moilliet, John S.
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