The Gas-Phase Reactivity ofp-Me3Si-Substituted 1,3-Diphenylpropane Towards Charged Electrophiles: Intra- and Interannular Hydrogen Migrations

Crestoni, Maria Elisa

doi:10.1002/(sici)1521-3765(19980615)4:6<993::aid-chem993>3.0.co;2-i

Cited by 6 publications

(2 citation statements)

References 17 publications

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“…Hence it appeared again that the neutral a,w-diarylalkane constituent within the I/N complex is coordinated to the carbenium ion with both of its aromatic units, that is as a truly bisolvating partner, rather than to display any intrinsic properties of the individual benzylic moieties. 26,[75][76][77][78][79] (See also Note b, at the end of this paper.) The convergent picture of the competing intra-complex proton and regioselective hydride transfer was further corroborated by an extended investigation of the fragmentation of metastable [M + H] + ions of a series of 4-tert-butylsubstituted 1,3-diarylpropanes bearing two or more methyl residues on one or both of the aromatic rings.…”

Section: Competing Intra-complex Hydride and Proton Transfer Processesmentioning

confidence: 96%

Concomitant Hydride and Proton Transfer: An Essay on Competing and Consecutive Key Reactions Occurring in Gaseous Ion/Neutral Complexes

Kuck

2012

Eur J Mass Spectrom (Chichester)

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The interplay of proton transfer and hydride transfer reactions in alkylbenzenium ions and related protonated di- and oligophenylalkanes is presented and discussed. While intra- and interannular proton exchange has been recognised to be an ubiquitous feature in protonated arenes, hydride abstraction is much less obvious but can become a dominating fragmentation channel in metastable ions of tert-butyl-substituted alkylbenzenium ions and related carbocations. In such cases, proton-induced release of the tert-butyl cation gives rise to ion/neutral complexes as reactive intermediates, for example, [(CH(3))(3)C(+)...arylCH(2)(α)(CH(2))(n)CH(2)(ω)aryl '] with n ≥ 0, and highly regioselective intra-complex hydride transfer occurs from all of the benzylic methylene hydride ion donor groups (α-CH(2) and ω-CH(2)) to the tert-butyl cation acting as a Lewis acid. Substituent effects on the individual contributions to the overall hydride transfer from different donor sites, including ortho-methyl groups, in particular, and the concomitant intra- complex proton transfer from the tert-butyl cation to the neutral diarylalkane constituent corroborate the view of "bisolvated" complexes as the central intermediates, in which the carbenium ion is coordinated to both of the aromatic π-electron systems. The role of cyclisation processes converting the benzylic, [M - H](+) type, ions into the isomeric benzenium, [M + H](+)-type, ions prior to fragmentation is demonstrated for several cases. This overall scenario, consisting of consecutive and/or competing intra-complex hydride abstraction and proton transfer, intraannular proton shifts (H+ ring walk) and interannular proton transfer, hydrogen exchange ("scrambling") processes, and cyclisation and other electrophilic substitution reactions, is of general importance in this field of gas-phase ion chemistry, and more recent examples concerning protonated ethers, benzylpyridinium and benzylammmonium ions are discussed in which these recurring features play central and concerted mechanistic roles as well.

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Section: Competing Intra-complex Hydride and Proton Transfer Processesmentioning

confidence: 96%

Concomitant Hydride and Proton Transfer: An Essay on Competing and Consecutive Key Reactions Occurring in Gaseous Ion/Neutral Complexes

Kuck

2012

Eur J Mass Spectrom (Chichester)

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“…Following these gas phase studies demonstrating the key role of deprotonation, the aromatic silylation of toluene by R 3 SiCl under AlCl 3 catalysis has been successfully accomplished in the presence of hindered tertiary amines by Olah et al, although in only moderate yield [23]. In the gas phase, not only benzene but also toluene and other aromatic and heteroaromatic compounds have been successfully silylated [24][25][26][27][28]. The silylium ions were formed in a gaseous environment at atmospheric pressure using a radiolytic approach [29].…”

Section: Introductionmentioning

confidence: 99%

Isomeric C5H11Si+ ions from the trimethylsilylation of acetylene: An experimental and theoretical study

Siehl

Brixner

Coletti

et al. 2013

International Journal of Mass Spectrometry

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Protonated 1,3,5-cycloheptatriene and 7-alkyl-1,3,5-cycloheptatrienes in the gas phase: ring contraction to the isomeric alkylbenzenium ions

Mormann

Kuck

1999

J. Mass Spectrom.

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The Gas-Phase Reactivity ofp-Me3Si-Substituted 1,3-Diphenylpropane Towards Charged Electrophiles: Intra- and Interannular Hydrogen Migrations

Abstract: The gas-phase reaction of pMe 3 SiC 6 H 4 (CH 2 ) 3 adducts, adequately described by the Wheland scomplex model, does not exclude the intermediacy of an ion ± neutral noncovalent complex.

Cited by 6 publications

References 17 publications

Concomitant Hydride and Proton Transfer: An Essay on Competing and Consecutive Key Reactions Occurring in Gaseous Ion/Neutral Complexes

Concomitant Hydride and Proton Transfer: An Essay on Competing and Consecutive Key Reactions Occurring in Gaseous Ion/Neutral Complexes

Isomeric C5H11Si+ ions from the trimethylsilylation of acetylene: An experimental and theoretical study

Protonated 1,3,5-cycloheptatriene and 7-alkyl-1,3,5-cycloheptatrienes in the gas phase: ring contraction to the isomeric alkylbenzenium ions

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