Site-specific hydrogen exchange and hydrogen transfer processes preceding the fragmentation of long-lived radical cations of ethyl dihydrocinnamate and related arylalkanoates

Amick, Aaron W.; Hoegg, Edward D.; Harrison, Sean; Houston, Katelyn R.; Hark, Richard R.; Reingold, I. David; Barth, Dieter; Letzel, Matthias C.; Kuck, Dietmar

doi:10.1016/j.ijms.2012.01.005

Cited by 7 publications

(10 citation statements)

References 28 publications

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“…As shown in Scheme , the corresponding proton is mobilized and assumed to undergo a 1,2‐shift along the aromatic ring and thus to weaken the otherwise rather strong C ar OMe bond. This mechanistic scenario is in line with nowadays accepted isomerization and fragmentation chemistry of gaseous aromatic ions . However, it may be noted that the minor loss of water, giving rise to ions at m / z 457.2050, from the protonated ester species indicates more complex, hidden rearrangements.…”

Section: Resultssupporting

confidence: 83%

The unusual fragmentation of long‐chain feruloyl esters under negative ion electrospray conditions

et al. 2019

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Long‐chain ferulic acid esters, such as eicosyl ferulate (1), show a complex and analytically valuable fragmentation behavior under negative ion electrospay collision‐induced dissociation ((−)‐ESI‐CID) mass spectrometry, as studied by use of a high‐resolution (Orbitrap) mass spectrometer. In a strong contrast to the very simple fragmentation of the [M + H]+ ion, which is discussed briefly, the deprotonated molecule, [M – H]−, exhibits a rich secondary fragmentation chemistry. It first loses a methyl radical (MS2) and the ortho‐quinoid [M – H – Me]‐• radical anion thus formed then dissociates by loss of an extended series of neutral radicals, CnH2n + 1• (n = 0–16) from the long alkyl chain, in competition with the expulsion of CO and CO2 (MS3). The further fragmentation (MS4) of the [M – H – Me – C3H7]− ion, discussed as an example, and the highly specific losses of alkyl radicals from the [M – H – Me – CO]‐• and [M – H – Me – CO2]‐• ions provide some mechanistic and structural insights.

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Section: Resultssupporting

confidence: 83%

The unusual fragmentation of long‐chain feruloyl esters under negative ion electrospray conditions

et al. 2019

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“…Hidden cyclisation steps may give rise to dihydronaphthalene instead of 4-phenyl-1-butyne. 40,52 The ESI-CID mass spectra of the 2-(2-phenylethyl) chromones 2-4 bearing a hydroxy substituent at the remote phenyl ring reveal one more but quite striking detail on the fragmentation behaviour of the corresponding [M + H] + ions ( Figure 3). The protonated meta-isomer, [ O] + (m/z 161) has to be energetically extremely favourable.…”

Section: + H] +mentioning

confidence: 99%

Fragmentation of Protonated 2-(2-Phenylethyl)Chromones from Agarwood: The Diagnostic Role of Ion/Neutral Complexes as Reactive Intermediates

Yang

Xia

Jiang

et al. 2015

Eur J Mass Spectrom (Chichester)

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A positive-ion electrospray ionisation collision-induced dissociation mass spectrometric study on the fragmentation of the [M + H](+) ions of 2-(2-phenylethyl)chromone and a set of nine hydroxyl- and/or methoxy-substituted derivatives has revealed a highly prominent fragmentation channel, the loss of benzoquinomethanes or a benzaldehyde, respectively, as a diagnostic feature for 2-(2-phenylethyl)chromones that bear a hydroxyl group at the para- (4'-), ortho- (2'-) and/or benzylic (α-) position of the phenylethyl residue. Derivatives that bear only a meta- (3'-) hydroxyl group do not undergo this elimination. The intermediacy of ion/neutral complexes (INCs) is invoked to explain this fragmentation, which involves the remarkable intra-complex proton or hydrogen atom transfer from the remote 4'-OH (or the 2'- or α-OH) functionalities. Density functional theory (B3LYP/6-31G(d)) calculations confirm the energetic preference for these elimination channels and agree with the limited thermochemical data known for para- and ortho- benzoquinomethanes. The INC-mediated losses of the benzaldehydes from the [M + H](+) ions of the α-hydroxy-substituted 2-(2-phenylethyl)chromones correspond to a particularly facile (vinylogous) Grob fragmentation. The study may be viewed as a telling example of the diagnostic role of ion/neutral complexes as intermediates for the structural assignment of constitutional isomers by mass spectrometry.

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“…Electrospray ionization mass spectrometry (ESI-MS) has proven to be a powerful tool for studying molecular structures, mechanisms, and kinetics and has been used in many fields. [16][17][18][19][20][21][22][23][24][25][26][27][28] Gas-phase reactions can be employed to reveal obscure mechanisms and promote industry applications of ESI-MS. 20,24,29,30 The fragments of compounds are related to their structures, but sometimes, it is difficult to identify the corresponding structure just from the fragments. This is due to rearrangements commonly occurred in CID, which include proton transfer, 31,32 benzyl cation transfer, 33 ion/neutral complex (INC) 34,35 and mediated fragmentation.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular benzyl cation transfer in the gas‐phase fragmentation of protonated benzyl phenyl sulfones

et al. 2020

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In this study, the gas-phase fragmentations of protonated benzyl phenyl sulfones were investigated by electrospray ionization tandem mass spectrometry (ESI-MS n ).Upon collisional activation, several characteristic fragment ions were observed, and the similar results occurred with different substituted benzyl phenyl sulfones. A mechanism involving an intramolecular benzyl cation transfer and the formation of intermediate ion was proposed and further identified by density functional theory (DFT) calculations. In addition, a reference compound, benzenesulfinic acid benzyl ester, has been synthesized, and its protonated ion has the same gas-phase behavior as compared to the protonated benzyl phenyl sulfone. This work provides access to some insight into the intramolecular benzyl-transfer reactions of benzyl phenyl sulfones in the gas phase and orients the characteristic peaks in collision-induced dissociation spectrometry (CID-MS).

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Site-specific hydrogen exchange and hydrogen transfer processes preceding the fragmentation of long-lived radical cations of ethyl dihydrocinnamate and related arylalkanoates

Cited by 7 publications

References 28 publications

The unusual fragmentation of long‐chain feruloyl esters under negative ion electrospray conditions

The unusual fragmentation of long‐chain feruloyl esters under negative ion electrospray conditions

Fragmentation of Protonated 2-(2-Phenylethyl)Chromones from Agarwood: The Diagnostic Role of Ion/Neutral Complexes as Reactive Intermediates

Intramolecular benzyl cation transfer in the gas‐phase fragmentation of protonated benzyl phenyl sulfones

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