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Stereochemical Effects in the Mass Spectra of cis‐ and trans ‐2‐Aryl‐4a,5,6,7,8,8a‐hexahydroquinazolin‐4(3 H )‐ones
Author(s) -
Pihlaja Kalevi,
Himottu Marja,
Ovcharenko Vladimir,
Göndös György,
Gera Lajos,
Bernáth Gábor
Publication year - 1996
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19960131)10:2<214::aid-rcm465>3.0.co;2-z
Subject(s) - chemistry , electron ionization , fragmentation (computing) , ion , mass spectrum , dissociation (chemistry) , spectral line , aryl , collision induced dissociation , ring (chemistry) , hydrogen , mass spectrometry , hydrocarbon , analytical chemistry (journal) , computational chemistry , ionization , tandem mass spectrometry , organic chemistry , physics , alkyl , chromatography , astronomy , computer science , operating system
The electron‐impact (EI) and collision‐induced dissociation (CID) spectra of the title compounds were studied. The main fragmentation routes of M +· ions included losses of hydrocarbon species and the formation of ArCNH + cations. The geometry of ring annelation predictably affected the stabilities of the molecular ions and the relative abundances of some characteristic fragment ions. The abundance ratios [M−H] + /M +· , which were higher for trans ‐annelated isomers, correlated with the electronic effects of aromatic ring substituents. Molecular ions and [M−H] + ions of stereoisomers gave different CID spectra, suggesting that stereochemical differences are still preserved after the loss of hydrogen from M +· ions. The stereochemical effects in the EI spectra were more pronounced at lower impact energies (16–24 eV). Several criteria for differentiating cis‐ and trans‐ annelated isomers based on the relative abundances of characteristic fragment ions were established.