Intramolecular hydrogen transfer in mass spectra. III. Rearrangements involving the loss of small neutral molecules

Kingston, David G. I.; Hobrock, Brice W.; Bursey, Maurice M.; Bursey, Joan T.

doi:10.1021/cr60298a002

Cited by 65 publications

(11 citation statements)

References 76 publications

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“…No other hydrogen atom can conveniently approach to within bonding distance as easily. It has frequently been observed under electronimpact conditions that neutral losses from cyclohexane rings involve 1,4-eliminations of this type [35], sometimes after conversion of chair to boat configurations [36]. A similar hydrogen migration from carbon to a linking oxygen atom has recently been proposed to account for the formation of Z-type ions in the dissociation of heparin dimers [27].…”

Section: Ions Produced By Fragmentation Of the Chitobiose Corementioning

confidence: 90%

Fragmentation of negative ions from carbohydrates: Part 2. Fragmentation of high-mannose N-linked glycans

Harvey

2005

J. Am. Soc. Mass Spectrom.

205

197

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[M + NO3]- And [M + (NO3)2]2- ions were produced by electrospray from neutral high-mannose ([Man](5-9)[GlcNAc]2, [Glc](1-3)[Man](4-9)[GlcNAc]2) N-linked glycans and their 2-aminobenzamide derivatives sprayed from methanol:water containing ammonium nitrate. Low energy collision-induced decomposition (CID) spectra of both types of ions were almost identical and dominated by cross-ring and C-type fragments, unlike the corresponding spectra of the positive ions that contained mainly B- and Y-type glycosidic fragments. This behavior could be rationalized by an initial proton abstraction from various hydroxy groups by the initially-formed anionic adduct. These negative ion spectra were more informative than the corresponding positive ion spectra and contained prominent ions that were diagnostic of structural features such as the composition of individual antennas that were not easily obtainable by other means. C-ions defined the sequence of the constituent monosaccharide residues. Detailed fragmentation mechanisms are proposed to account for many of the diagnostic ions.

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Section: Ions Produced By Fragmentation Of the Chitobiose Corementioning

confidence: 90%

Fragmentation of negative ions from carbohydrates: Part 2. Fragmentation of high-mannose N-linked glycans

Harvey

2005

J. Am. Soc. Mass Spectrom.

205

197

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“…('H92TMS derivatives were prepared by the use of ( Hl&s -trirnethyl~ilylacetamide.~ (17a,21,21,2 1 -H4)3P,16a-Dihydroxypregn-5-en-20-one was prepared by exchanging the hydrogens a to the ketone group of the parent steroid for deuterium by the use of 0.1 N NaO'H in ' H2O and dioxane. Reduction of this labelled steroid with lithium aluminium hydride gave the correspondingly labelled analogue of the trihydroxy 2 steroids 3p,16a,20a(and P)-trihydroxy-pregn-5-ene (18). Reduction of the unlabelled ketol (10) with lithium aluminium deuteride gave 3P,16a,20a(and P)-trihydro~y(20-~H)pregn-5-ene.…”

Section: Preparation Of Derivativesmentioning

confidence: 99%

Mass spectra of the trimethylsilyl ethers of some 3β-hydroxy-Δ5-C21 steroids

Harvey

Middleditch

Brooks

1982

Biol. Mass Spectrom.

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The mass spectra of the trimethylsilyl derivatives of 22 3P-hydroxy-A5-pregnenes have been examined with the aid of deuterium labelling and high resolution mass measurements. The influence of additional hydroxy and keto substituents on the characteristic fragment ions is discussed and fragmentation mechanisms for several ions characteristic of hydroxylation at specific sites (11 and 16) are proposed.

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“…To the authors, knowledge, although the structure of the latter fragment ion is shown to be CH 2 ῎C(OH)OCH 2 CH 3 ῌῌ which is an enol form of ethyl acetate, the mechanism of this fragmentation has not been elucidated at the present time.…”

Section: )῎4)mentioning

confidence: 89%

Unimolecular Reactions of Diethyl Malonate Cation in Gas-phase

Tajima

Ishiguro

Mamada

et al. 2004

J. Mass Spectrom. Soc. Jpn.

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Unimolecular reactions of diethyl malonate cation (CH3CH2OC(῎O)CH2C(῎O)OCH2CH3ῌῌ ; 1 ῌῌ , Mw : 160) induced by electron ionization, have been investigated by use of mass-analyzed ion kinetic energy (MIKE) spectrometry and D-labeling in conjunction with thermochemistry. In the metastable time window, the molecular ions ῌ ) ions decompose into the ions at m/z 115, 106, and 105 by the losses of H2O, C2H3, and C2H4, respectively. A large part of the first fragment ions would be in the keto form and it decomposes into the m/z 71 and 43 ions by the losses of CO2 and C3H4O2 (or C2O3), and a small part would be in the enol form and decomposes into the m/z 87 ions by the loss of C2H4, not CO. The m/z 43 ions are isobaric, C2H3Oῌ and C3H7 ῌ .

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Intramolecular hydrogen transfer in mass spectra. III. Rearrangements involving the loss of small neutral molecules

Cited by 65 publications

References 76 publications

Fragmentation of negative ions from carbohydrates: Part 2. Fragmentation of high-mannose N-linked glycans

Fragmentation of negative ions from carbohydrates: Part 2. Fragmentation of high-mannose N-linked glycans

Mass spectra of the trimethylsilyl ethers of some 3β-hydroxy-Δ5-C21 steroids

Unimolecular Reactions of Diethyl Malonate Cation in Gas-phase

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