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Electron impact mass spectra of 1,3,4-thiadiazolo[3,2-a]pyrimidin-7-one and isomeric-5-one derivatives

✍ Scribed by S. Foti; F. Russo; A. Santagati; M. Santagati

Publisher
John Wiley and Sons
Year
1984
Tongue
English
Weight
401 KB
Volume
19
Category
Article
ISSN
1076-5174

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✦ Synopsis

Abstract

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.

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