Electron ionization mass spectra of some diexo norbornane- and norbornene-fused phenyl-substituted 1,3-oxazines and related systems. Competitive retro-Diels-Alder fragmentations in 4-phenyl-4a,5,8,8a-tetrahydro-5,8-methano-4H-benzo[e]1,3-oxazines

Kalevi Pihlaja, Marja Himottu, Vladimir Ovcharenko, Samuel Frimpong-Manso, Géza Stájer

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The electron ionization spectra of seven diexo norbornane- and norbornene-fused six- and seven-membered heterocycles containing O and N in positions 1 and 3 are reported. Molecular ions of norbornane-fused oxazines, especially the 2-anilino derivative, underwent retro-Diels-Alder fragmentation leading to a cleavage of the heterocyclic ring whereas, in norbornene-fused compounds, two concurrent retro-Diels-Alder fragmentations occurred. Fragmentation patterns of norbornane-fused oxazin-2-ones(or -thiones) are closely related to each other and, in some cases, provide evidence for the presence of minor amounts of the ionized open-chain tautomers in the gas phase. The ionized molecular ions of the 2-anilino derivatives appear to exist as mixtures of 2-phenylimino and 2-anilino isomers with exo- and endocyclic C = N bonds, respectively.

Original languageEnglish
Pages (from-to)249-252
Number of pages4
JournalRapid Communications in Mass Spectrometry
Volume11
Issue number3
DOIs
Publication statusPublished - Jan 1 1997

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry

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