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Electron impact mass spectra of 1,3,4‐thiadiazolo[3,2‐ a ]pyrimidin‐7‐one and isomeric‐5‐one derivatives
Author(s) -
Foti S.,
Russo F.,
Santagati A.,
Santagati M.
Publication year - 1984
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.1210190906
Subject(s) - mass spectrum , chemistry , electron ionization , metastability , spectral line , ring (chemistry) , mass , electron , computational chemistry , mass spectrometry , medicinal chemistry , organic chemistry , ionization , ion , chromatography , physics , quantum mechanics , astronomy
The 70 eV electron impact mass spectra of some 1,3,4‐thiadiazolo[3,2‐ a ]pyrimidin‐7‐one and isomeric‐5‐one derivatives are discussed with the aid of defocused metastable spectra and exact mass measurements. The compounds are shown to be very stable to electron impact and ring contraction reactions are in most cases the characterstic fragmentations. Most importantly, the 7‐one derivatives fragment by a retro‐Diels–Alder process which does not occur in the 5‐one isomers. This provides a diagnostic tool for differentiation between the isomers and for the unequivocal assignment of the structure.