Electron ionization mass spectra of some cyclohexane fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and related thiazines

Kalevi Pihlaja, Lenita Lötjönen, F. Fülöp, G. Bernáth, Pirjo Vainiotalo

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The 70 eV electron ionization mass spectra of six cyclohexane fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and six related thiazines were recorded and their fragmentation patterns were studied by metastable‐ion analysis and exact mass measurement. All the compounds examined lost a hydrogen atom from their molecular ion in a process best described as intramolecular cyclization. The most typical fragmentations were the loss of various alkyl radicals from the M or [MH]+ ions with the simultaneous migration of one or more hydrogen atoms from the carbocyclic part to the heterocyclic part of the molecule. N‐Substitution clearly affected the type and extent of different reactions. In general, the fragmentation patterns of the thiazine derivatives were more complicated than those of the related oxazines. In all cases studied, the cis‐ and trans‐fused isomers gave rise to so similar spectra that their adequate differentiation was not possible.

Original languageEnglish
Pages (from-to)279-282
Number of pages4
JournalRapid Communications in Mass Spectrometry
Issue number8
Publication statusPublished - 1990


ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry

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