Electron impact mass spectral fragmentation of 3a,5-disubstituted 1,3-diphenyl-3a,4,5,6-tetra-hydro-3H-1,2,4-triazolo[4,3-a][1,5]benzo-diazepines

Xu, Jiaxi; Zhang, Qihan; Wang, Chenbo

doi:10.1002/1097-0231(20001230)14:24<2339::aid-rcm170>3.0.co;2-l

Cited by 5 publications

(1 citation statement)

References 19 publications

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“…Recently, several ring contraction reactions have been reported in the literature: e.g. eight‐membered 1,6‐benzothiazocines undergo a ring contraction to form 1,4‐benzothiazines by elimination of alkene;2 seven‐membered heterocyclic 1,5‐benzodiazepine and 1,5‐benzothiazepine tricyclic derivatives undergo a four‐membered ring rearrangement to form benzimidazoles and benzothiazoles by loss of an alkene molecule;3–10 seven‐membered ring 3‐hydroxy‐1,4‐benzodiazepines produce stable aromatic structures by the elimination of water after ring contraction;11 five‐membered heterocyclic ring 1,3‐dioxolanes yield cyclopropanes by loss of ketone;12 oxazolines produce aziridines by loss of aldehydes and ketones; pyrrolidines give rise to cyclopropane by loss of imines; oxazolidine derivatives undergo a ring contraction to form aziridines by loss of aldehydes;13–15 four‐membered ring azetidinones produce aziridines by loss of carbon monoxide,16–18 and so on.…”

Section: Structures Of Compounds 1–10mentioning

confidence: 99%

Ring contraction reactions of 2,3‐dihydro‐4H‐1,3‐oxazin‐4‐ones under electrospray ionization conditions

Liu

Chen

et al. 2004

Rapid Comm Mass Spectrometry

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The mass spectral behavior of 2,3-dihydro-4H-1,3-oxazin-4-ones has been investigated using electrospray ionization multi-stage mass spectrometry (ESI-MS(n)). All compounds showed a predominant retro-Diels-Alder (RDA) fragmentation pathway, and a novel ring contraction reaction by loss of isocynates was also found. The fragmentation mechanisms proposed for 4H-1,3-oxazin-4-ones are supported by ESI-MS/MS/MS spectra.

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Section: Structures Of Compounds 1–10mentioning

confidence: 99%

Ring contraction reactions of 2,3‐dihydro‐4H‐1,3‐oxazin‐4‐ones under electrospray ionization conditions

Liu

Chen

et al. 2004

Rapid Comm Mass Spectrometry

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Current literature in mass spectrometry

2001

J. Mass Spectrom.

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In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (3 Weeks journals ‐ Search completed at 27th. Dec. 2000)

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Mass spectral fragmentation of (S,S)‐2‐substituted 4,4‐diphenyl‐3,1‐oxazabicyclo[3.3.0]octanes: ring contraction of pyrrolidine and 1,3‐oxazolidine in mass spectrometry

Zuo

2003

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The mass spectral behaviour of (S,S)-2-substituted 4,4-diphenyl-3,1-oxazabicyclo[3.3.0]octanes has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under fast atom bombardment (FAB) and electron impact (EI) ionization conditions. Under FAB ionization, all compounds show a tendency to form protonated aldehyde or benzophenone ions and to form protonated 1-azabicyclo[3.1.0]hexane ions, which can further lose an ethylene or cyclopropane from the pyrrolidine ring to produce protonated 1-azabicyclo[1.1.0]butane ions and 3H-azirine ions, respectively. Under EI ionization, a similar fragmentation to that under FAB ionization was observed. The title compounds also show a tendency to yield oxirane ions and oxirenium ions by loss of pyrrolidine and pyrrolidine plus H. Ring contractions of 1,3-oxazolidine by loss of an aldehyde or ketone and of pyrrolidine by loss of an ethylene or cyclopropane were observed under both FAB and EI ionization conditions.

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Electron impact mass spectral fragmentation of 3a,5-disubstituted 1,3-diphenyl-3a,4,5,6-tetra-hydro-3H-1,2,4-triazolo[4,3-a][1,5]benzo-diazepines

Cited by 5 publications

References 19 publications

Ring contraction reactions of 2,3‐dihydro‐4H‐1,3‐oxazin‐4‐ones under electrospray ionization conditions

Ring contraction reactions of 2,3‐dihydro‐4H‐1,3‐oxazin‐4‐ones under electrospray ionization conditions

Current literature in mass spectrometry

Mass spectral fragmentation of (S,S)‐2‐substituted 4,4‐diphenyl‐3,1‐oxazabicyclo[3.3.0]octanes: ring contraction of pyrrolidine and 1,3‐oxazolidine in mass spectrometry

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