Gas‐Phase Nucleophilic Aromatic Substitution between Piperazine and Halobenzyl Cations: Reactivity of the Methylene Arenium Form of Benzyl Cations

Chai, Yunfeng; Jiang, Kezhi; Sun, Cuirong; Pan, Yuanjiang

doi:10.1002/chem.201101790

Cited by 36 publications

(40 citation statements)

References 66 publications

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“…The reaction of the ring-charged methylene arenium ion is unknown, except when it is coordinated to a metal center in solution [5] or constrained by steric effect in the gas phase [7]. We recently reported a gas-phase nucleophilic substitution reaction between piperazine and methylene arenium ions at the non-restricted state in mass spectrometry [8].…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Chemistry of Benzyl Cations in Dissociation ofN-Benzylammonium andN-Benzyliminium Ions Studied by Mass Spectrometry

Chai

Wang

Sun

et al. 2012

J. Am. Soc. Mass Spectrom.

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In this study, the fragmentation reactions of various N-benzylammonium and N-benzyliminium ions were investigated by electrospray ionization mass spectrometry. In general, the dissociation of N-benzylated cations generates benzyl cations easily. Formation of ion/neutral complex intermediates consisting of the benzyl cations and the neutral fragments was observed. The intra-complex reactions included electrophilic aromatic substitution, hydride transfer, electron transfer, proton transfer, and nucleophilic aromatic substitution. These five types of reactions almost covered all the potential reactivities of benzyl cations in chemical reactions. Benzyl cations are well-known as Lewis acid and electrophile in reactions, but the present study showed that the gas-phase reactivities of some suitably ring-substituted benzyl cations were far richer. The 4-methylbenzyl cation was found to react as a Brønsted acid, benzyl cations bearing a strong electron-withdrawing group were found to react as electron acceptors, and parahalogen-substituted benzyl cations could react as substrates for nucleophilic attack at the phenyl ring. The reactions of benzyl cations were also related to the neutral counterparts. For example, in electron transfer reaction, the neutral counterpart should have low ionization energy and in nucleophilic aromatic substitution reaction, the neutral counterpart should be piperazine or analogues. This study provided a panoramic view of the reactions of benzyl cations with neutral N-containing species in the gas phase.

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Section: Introductionmentioning

confidence: 99%

Gas-Phase Chemistry of Benzyl Cations in Dissociation ofN-Benzylammonium andN-Benzyliminium Ions Studied by Mass Spectrometry

Chai

Wang

Sun

et al. 2012

J. Am. Soc. Mass Spectrom.

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“…However, the transfer of a halogen atom in unimolecular fragmentation of organohalogen compounds in mass spectrometry is rare except for examples of F-atom migration [16][17][18][19][20]. In fact, loss of hydrogen halide or halogen radical is the regular fragmentation pathway for organohalogen compounds [21][22][23].…”

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confidence: 99%

Intramolecular Halogen Transfer via Halonium Ion Intermediates in the Gas Phase

Chai

Xiong²,

Yue

et al. 2015

J. Am. Soc. Mass Spectrom.

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Abstract. The fragmentation of halogen-substituted protonated amines and quaternary ammonium ions (R . A potential energy surface scan using DFT calculation for CH 2 -N bond cleavage process of protonated 2-bromo-N,N-dimethylethanamine supports the formation of this intermediate. The bromonium ion intermediate-involved halogen transfer mechanism is supported by an examination of the ion/molecule reaction between isolated ethylenebromonium ion and triethylamine, which generates the N-bromo-N,N,N-triethylammonium cation. For other halogens, Cl and I also can be involved in similar intramolecular halogen transfer, but F cannot be involved. With the elongation of the carbon chain between the halogen (bromine as a representative example) and amine, the migration ability of halogen decreases. When the carbon chain contains two or three CH 2 units (n = 1, 2), formal bromine cation transfer can take place, and the transfer is easier when n = 1. When the carbon chain contains four or five CH 2 units (n = 3, 4), formal bromine cation transfer does not occur, probably because the fiveand six-membered cyclic bromonium ions are very stable and do not donate the bromine to the amine.

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“…

[12]

RESULTS AND DISCUSSION

A typical tandem mass spectrum for [1 + H] + at m/z 347 is depicted in Fig.

…”

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confidence: 99%

“…[2] However, MS n -based structural elucidation has been challenging due to the widespread rearrangement reactions induced by ion-neutral complexes (INCs), [7][8][9][10] such as proton transfer, [8] electron transfer, [7,8] hydride transfer, [8] electrophilic aromatic substitution, [9] and nucleophilic aromatic substitution, [10] which have attracted the interest of many mass spectrometrists.…”

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Two competitive INC‐mediated reactions in the gas‐phase fragmentation of protonated indolyl benzo[b]carbazoles

Zhang

Jiang

Zou

et al. 2016

Rapid Comm Mass Spectrometry

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Mass spectrometry (MS) is commonly used nowadays in the structural analysis of a large variety of compounds, [1][2][3][4][5][6] including drugs, [5,6] metabolites, [3] particles, [1] intermediates, [4] and forensic evidence.[2] However, MS n -based structural elucidation has been challenging due to the widespread rearrangement reactions induced by ion-neutral complexes (INCs), [7][8][9][10] such as proton transfer, [8] electron transfer, [7,8] hydride transfer, [8] electrophilic aromatic substitution, [9] and nucleophilic aromatic substitution, [10] which have attracted the interest of many mass spectrometrists.Benzo [b]carbazoles are widely distributed in alkaloids and pharmaceuticals, which exhibit antitumor and antibiotic activities.[ [11] The direct infusion experiments were performed on a quadrupole time-of-flight (QTOF) mass spectrometer from (Bruker Daltonics, MA, USA) equipped with an ESI interface in positive ion mode. Typical parameters were set in the experiments, and theoretical calculations were performed by the density functional theory (DFT) method.[12] RESULTS AND DISCUSSIONA typical tandem mass spectrum for [1 + H] + at m/z 347 is depicted in Fig. 1(a + , respectively. Another abundant ion at m/z 332 (ion E) is generated by the loss of a methyl radical via the homolytic cleavage of the C2′-C8′ bond (not pursued here).[13] The elemental compositions of these fragment ions have also been confirmed by accurate mass data (Supplementary Table S1, Supporting Information). The potential pathways for generation of ions A, B, C, and D are proposed in Scheme 2.Prior to rationalization of the fragmentation of [1 + H] + , we should first investigate the potential protonation sites of the molecule.[12] The relative energies of the structures with different protonation sites are summarized in Supplementary Table S2 (Supporting Information). From calculation results, the C6 atom, rather than the aromatic amine N5, is the most

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Gas‐Phase Nucleophilic Aromatic Substitution between Piperazine and Halobenzyl Cations: Reactivity of the Methylene Arenium Form of Benzyl Cations

Cited by 36 publications

References 66 publications

Gas-Phase Chemistry of Benzyl Cations in Dissociation ofN-Benzylammonium andN-Benzyliminium Ions Studied by Mass Spectrometry

Gas-Phase Chemistry of Benzyl Cations in Dissociation ofN-Benzylammonium andN-Benzyliminium Ions Studied by Mass Spectrometry

Intramolecular Halogen Transfer via Halonium Ion Intermediates in the Gas Phase

Two competitive INC‐mediated reactions in the gas‐phase fragmentation of protonated indolyl benzo[b]carbazoles

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