Mass-spectral study of heterocyclic analogs of 4-dimethylamino- and 4-azidochalcones

Abstract

The predominant pathway in the mass-spectral fragmentation of 4-dimethylamino- and 4-azidochalcones under the influence of electron impact is cleavage of the aryl-CO and CO-CH bonds and localization of the charge on the fragment with the lower ionization energy. The characteristic “chalcone” rearrangement with the ejection of a molecule of CO from the molecular ion and subsequent cyclization and aromatization of the stilbene derivative is also observed; in the case of azides this process takes place only after the loss of a molecule of nitrogen by the molecular ion. The differences in the pathways of fragmentation of the hetero analogs make it possible to identify compounds with α, Β, and γ orientations of the substituent relative to the heteroring nitrogen atom.