Poly‐oniosubstituierte Chinone als starke Elektronenacceptoren

Weiß, Robert; Salomon, Norbert J.; Miess, Georg E.; Roth, Reinhard

doi:10.1002/ange.19860981024

Cited by 32 publications

(10 citation statements)

References 4 publications

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“…The reaction of the amidinate Si I dimer [LSiD] 2 (1) [9] with one equivalent of N-trimethylsilyl-4-dimethylaminopyridinium triflate, [4-NMe 2 C 5 H 4 NSiMe 3 ]OTf, [10] and two equivalents of DMAP in THF at room temperature afforded [LSi-A C H T U N G T R E N N U N G (DMAP)]OTf (2) in 54 % yield (Scheme 2). The byproduct is Me 3 Si À SiMe 3 , the structure of which was confirmed by 29 Si and 1 H NMR spectroscopy and mass spectrometry.…”

Section: Resultsmentioning

confidence: 99%

“…OTf were prepared as described in the literature. [9,10] The 1 H, 13 C, 19 F, and 29 Si NMR spectra were recorded using a JEOL ECA 400 spectrometer. The chemical shifts (d) are relative to SiMe 4 for 1 H, 13 C, and 29 Si; and CFCl 3 for 19 F. Elemental analyses were performed by the Division of Chemistry and Biological Chemistry, Nanyang Technological University.…”

Section: Methodsmentioning

confidence: 99%

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A Silyliumylidene Cation Stabilized by an Amidinate Ligand and 4‐Dimethylaminopyridine

Yeong

et al. 2013

Chemistry A European J

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The synthesis and reactivity of a silyliumylidene cation stabilized by an amidinate ligand and 4-dimethylaminopyridine (DMAP) are described. The reaction of the amidinate silicon(I) dimer [LSi:]2 (1; L = PhC(NtBu)2) with one equivalent of N-trimethylsilyl-4-dimethylaminopyridinium triflate [4-NMe2C5H4NSiMe3]OTf and two equivalents of DMAP in THF afforded [LSi(DMAP)]OTf (2). The ambiphilic character of 2 is demonstrated from its reactivity. Treatment of 2 with 1 in THF afforded the disilylenylsilylium triflate [L'2(L)Si]OTf (3; L' = LSi:) with the displacement of DMAP. The reaction of 2 with [K{HB(iBu)3}] and elemental sulfur in THF afforded the silylsilylene [LSiSi(H){(NtBu)2C(H)Ph}] (4) and the base-stabilized silanethionium triflate [LSi(S)DMAP]OTf (5), respectively. Compounds 2, 3, and 5 have been characterized by X-ray crystallography.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

A Silyliumylidene Cation Stabilized by an Amidinate Ligand and 4‐Dimethylaminopyridine

Yeong

et al. 2013

Chemistry A European J

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“…The product is dark brown and is not affected by addition of water. Condensation reactions occurring at positions 2 and 5 of chloranil, imparts stability analogous to poly-onio substituted quinones, as reported earlier [16].…”

Section: Synthesis Of Dcpbcmentioning

confidence: 73%

Silica gel-immobilized di[N-chloranil piperazinium-bis-sulfosalicylate]: Preparation, characterization and performance for chromatographic separation of metals

Singh

Srinivasan

2002

Chromatographia

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SummaryA chelating resin loaded with 5-sulfosahcylic acid, was prepared by ion-exchange. The resin, di-[N-chloranil piperazinium-bis-sulfosahcylate] was obtained by ion-exchange with piperazine-chloranil copolymer as matrix.A useful chromatographic packing is prepared by immobilizing the resin on silica gel. Detailed characterisation of this adsorbent has been carried out and selective adsorption conditions optimised for some heavy metals under static and dynamic conditions. The relatively fast kinetics of the adsorbent with time to reach half maximum adsorption (ti/2 = 2 min) and the level of attainment of equilibrium in 2 min (> 50%) reveal the suitability of the resin in column operation, especially in single column ion-chromatography. The metal ion content of the eluent was determined spectrophotometrically.

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“…Accordingly, we turned our attention to stronger electron acceptors at the C2 position. Introduction of a pentafluorophenyl moiety, for instance, would generate a substrate for the SASAPOS-protocol [26] and would thus allow the introduction of a pentaoniobenzene substituent at the C2 position. Reaction of 19 b with one equivalent of hexafluorobenzene, though, led to formation of the bis(imidazolium)derivative 23, which was isolated in 29 % yield (relative to hexafluorobenzene).…”

Section: Resultsmentioning

confidence: 99%

4,5‐Bis(dialkylamino)‐Substituted Imidazolium Systems: Facile Access to N‐Heterocyclic Carbenes with Self‐Umpolung Option

Huber¹,

Heinemann²,

Audebert

et al. 2011

Chemistry A European J

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The first synthesis of 4,5-bis-(dimethylamino)-substituted imidazolium compounds was developed, which is based on the reaction of a 1,2-diamino-1,2-bis(phosphonio)ethene with lithiated formamidines. This represents the first application of this class of ethene derivatives for the preparation of heterocycles. These N-heterocyclic carbene (NHC) precursors show a remarkably reduced basicity and nucleophilicity of their NMe2 groups, which is due to the strong anomeric interactions of the latter with the imidazolium core. According to DFT calculations, these NHCs are capable of self-umpolung if sufficiently strong acceptor substituents are introduced at the carbene center. To test the self-umpolung capabilities of the NHCs, various substituents were attached to the carbene center and the obtained compounds were characterized by single-crystal X-ray analysis as well as quantum chemical computations. Strong acceptor substituents are required to induce self-umpolung, such as in the phosphonio-substituted derivative, for which partial self-umpolung was found. The N,N′-bis(4-dimethylaminophenyl)-substituted imidazolium compound represents a special case, as it incorporates as much as three two-step redox systems within the NHC framework. This will probably result in a high electronic flexibility of the corresponding nucleophilic carbenes, especially when they serve as ligands in transition metal complexes.

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Poly‐oniosubstituierte Chinone als starke Elektronenacceptoren

Cited by 32 publications

References 4 publications

A Silyliumylidene Cation Stabilized by an Amidinate Ligand and 4‐Dimethylaminopyridine

A Silyliumylidene Cation Stabilized by an Amidinate Ligand and 4‐Dimethylaminopyridine

Silica gel-immobilized di[N-chloranil piperazinium-bis-sulfosalicylate]: Preparation, characterization and performance for chromatographic separation of metals

4,5‐Bis(dialkylamino)‐Substituted Imidazolium Systems: Facile Access to N‐Heterocyclic Carbenes with Self‐Umpolung Option

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