Mass spectra of new substituted 2-amino-4H-pyrans: a retro-Diels-Alder reaction pattern

Lucas, Ana de; Fernández‐Gadea, Javier; Martı́n, Nazario; Martín, Nazario; Seoane, Carlos

doi:10.1002/1097-0231(20001015)14:19<1783::aid-rcm92>3.0.co;2-1

Cited by 12 publications

(9 citation statements)

References 13 publications

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“…2). The ion at m/z 341 ( 1h ) could be well interpreted by the RDA cleavage of ring F to lose a C 11 H 14 O 5 part [22, 23]. Thus, the elimination of 44 Da can be attributed to the losses of C 2 H 4 O and CO 2 to yield product ions 1j ( m/z 297.0792) and 1j′ ( m/z 297.1105) [24].…”

Section: Resultsmentioning

confidence: 99%

A Fragmentation Study on Four Unusual Secoiridoid Trimers, Swerilactones H–K, by Electrospray Tandem Mass Spectrometry

Geng

Chen

2016

Nat. Prod. Bioprospect.

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Swerilactones H–K (1–4) as four unprecedented secoiridoid trimers represent a new type of natural product, which has attracted much interest of natural chemists due to their novel skeletons and promising bioactivity. In order to well understand their MS fragmentation behaviors, they were investigated by electrospray ionization ion-trap time-of-flight multistage product ion mass spectrometry (ESI-IT-TOF-MSn) for the first time. The protonated molecules ([M+H]+) of swerilactones J and K, and deprotonated molecules ([M−H]−) of swerilactones H, J and K were readily observed in the conventional single-stage mass spectra (MS); however only the [M+Cl]− ion for swerilactone I was obtained in negative mode. Based on the MSn study, the fragmentation pathways of swerilactones H and I in negative mode, and swerilactones J and K in both positive and negative modes were proposed. The neutral losses of H2O, CO, CO2 and C2H4O moieties are the particular elimination from the precursor ions due to the presence of hydroxyl, δ-lactone and 1-O-ethyl moieties in their structures, of which the retro-Diels–Alder cleavage was the most particular dissociation. The fragment ions at m/z 341 and 291 in negative mode can be considered as the diagnostic ions for secoiridoid trimers. This investigation will provide valuable information for their fast characterization from complicated natural mixtures and extensive understanding their structural architectures.Electronic supplementary materialThe online version of this article (doi:10.1007/s13659-016-0114-6) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

A Fragmentation Study on Four Unusual Secoiridoid Trimers, Swerilactones H–K, by Electrospray Tandem Mass Spectrometry

Geng

Chen

2016

Nat. Prod. Bioprospect.

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“…While the MS/MS spectrum of sodium‐cationized isomer 1 ( m/z 290) shows both the Boc‐characteristic ions at m/z 234 (loss of C 4 H 8 ) and m/z 190 [M+Na–Boc+H] + (100%), the CID of [ 2 +Na] + yields only the former ion with increased abundance (100%) and the latter is totally absent. Interestingly the Boc‐free peptide ion of 1 at m/z 190 undergoes a retro‐Diels‐Alder fragmentation31–40 by the loss of cyclopentadiene (C 5 H 6 , loss of 66 u), to form the m/z 124 ion, which is totally absent for 2 . In the case of 2 , the same retro‐Diels‐Alder fragmentation from [M+Na–C 4 H 8 ] + ( m/z 234) leads to the m/z 168 ion which is absent in 1 .…”

Section: Resultsmentioning

confidence: 99%

Diastereomeric differentiation of norbornene amino acid peptides by electrospray ionization tandem mass spectrometry

Raju

Ramesh

Sudhakar

et al. 2009

Rapid Comm Mass Spectrometry

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A new class of diastereomeric pairs of non-natural amino acid peptides derived from butyloxycarbonyl (Boc-)protected cis-(2S,3R)- and trans-(2S,3S)-beta-norbornene amino acids including a monomeric pair have been investigated by electrospray ionization (ESI) tandem mass spectrometry using quadrupole time-of-flight (Q-TOF) and ion-trap mass spectrometers. The protonated cis-BocN-beta-nbaa (2S,3R) (1) (betanbaa = beta-norbornene amino acid) eliminates the Boc group to form [M+H-Boc+H](+), whereas an additional ion [M+H-C(4)H(8)](+) is formed from trans-BocN-beta-nbaa (2S,3S) (2). Similarly, it is observed that the peptide diastereomers (di-, tri- and tetra-), with cis-BocN-beta-nbaa (2S,3R)- at the N-terminus, initially eliminate the Boc group to form [M+H-Boc+H](+) which undergo further fragmentation to give a set of product ions that are different for the peptides with trans-BocN-beta-nbaa (2S,3S)- at the N-terminus. Thus the Boc group fragments differently depending on the configuration of the amino acid present at the N-terminus. It is also observed that the peptide bond cleavage in these peptides is less favoured and most of the product ions are formed due to retro-Diels-Alder fragmentation. Interestingly, sodium-cationized peptide diastereomers mainly yield a series of retro-Diels-Alder fragment ions which are different for each diastereomer as they are formed starting from [M+Na-Boc+H](+) in peptides with cis-BocN-beta-nbaa (2S,3R)- at the N-terminus, and [M+Na-C(4)H(8)](+) in peptides with trans-BocN-beta-nbaa (2S,3S)- at the N-terminus. All these results clearly indicate that these diastereomeric pairs of peptides yield characteristic product ions which help distinguish the isomers.

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“…Computational quantum calculations provide the information required to identify the ionization sites and the stability of each ionic species formed during the fragmentation in MS/MS experiments . Thus, the combination of MS/MS with computational chemistry provides valuable information for understanding gas‐phase fragmentation and to support the characterization of organic compounds in general …”

Section: Introductionmentioning

confidence: 99%

Gas‐phase fragmentation of protonated piplartine and its fungal metabolites using tandem mass spectrometry and computational chemistry

et al. 2017

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Piplartine, an alkaloid produced by plants in the genus Piper, displays promising anticancer activity. Understanding the gas-phase fragmentation of piplartine by electrospray ionization tandem mass spectrometry can be a useful tool to characterize biotransformed compounds produced by in vitro and in vivo metabolism studies. As part of our efforts to understand natural product fragmentation in electrospray ionization tandem mass spectrometry, the gas-phase fragmentation of piplartine and its two metabolites 3,4-dihydropiplartine and 8,9-dihydropiplartine, produced by the endophytic fungus Penicillium crustosum VR4 biotransformation, were systematically investigated. Proposed fragmentation reactions were supported by ESI-MS/MS data and computational thermochemistry. Cleavage of the C-7 and N-amide bond, followed by the formation of an acylium ion, were characteristic fragmentation reactions of piplartine and its analogs. The production of the acylium ion was followed by three consecutive and competitive reactions that involved methyl and methoxyl radical eliminations and neutral CO elimination, followed by the formation of a four-member ring with a stabilized tertiary carbocation. The absence of a double bond between carbons C-8 and C-9 in 8,9-dihydropiplartine destabilized the acylium ion and resulted in a fragmentation pathway not observed for piplartine and 3,4-dihydropiplartine. These results contribute to the further understanding of alkaloid gas-phase fragmentation and the future identification of piplartine metabolites and analogs using tandem mass spectrometry techniques. Copyright © 2017 John Wiley & Sons, Ltd.

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Mass spectra of new substituted 2-amino-4H-pyrans: a retro-Diels-Alder reaction pattern

Cited by 12 publications

References 13 publications

A Fragmentation Study on Four Unusual Secoiridoid Trimers, Swerilactones H–K, by Electrospray Tandem Mass Spectrometry

A Fragmentation Study on Four Unusual Secoiridoid Trimers, Swerilactones H–K, by Electrospray Tandem Mass Spectrometry

Diastereomeric differentiation of norbornene amino acid peptides by electrospray ionization tandem mass spectrometry

Gas‐phase fragmentation of protonated piplartine and its fungal metabolites using tandem mass spectrometry and computational chemistry

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