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Electron impact and chemical ionization mass spectra of norbornane/ene di‐ exo and di‐ endo ‐fused 1,3‐oxazin‐2(1 H )‐ones and 1,3‐oxazine‐2(1 H )‐thiones
Author(s) -
Partanen Tuula,
Vainiotalo Pirjo,
Stájer Géza,
Bernáth Gábor,
Pihlaja Kalevi
Publication year - 1990
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210251110
Subject(s) - norbornane , electron ionization , chemistry , fragmentation (computing) , mass spectrum , ene reaction , ionization , stereochemistry , dissociation (chemistry) , hydrogen , hydrogen atom , mass spectrometry , ion , analytical chemistry (journal) , medicinal chemistry , organic chemistry , alkyl , chromatography , computer science , operating system
Mass spectral fragmentations of four norbornane/ene di‐ exo ‐ and di‐ endo ‐fused 1,3‐oxazin‐2(1 H )‐ones and four 1,3‐oxazine‐2(1 H )‐thiones were examined by means of metastable ion analysis, the collision‐induced dissociation technique and exact mass measurement. Under electron impact (EI) conditions all the saturated compounds gave rise to complicated fragmentations, including several rearrangements. For the unsaturated compounds, a retro‐Diels‐Alder (RDA) process was the most favoured fragmentation pathway, which took place with hydrogen rearrangement to yield RDA + H fragments. The EI mass spectra did not permit isomeric differentiation. Under chemical ionization conditions, stereochemical effects were more perceptible, but isomeric differentiation was still difficult.