title: Stereospecific fragmentations in the mass spectra of stereoisomeric isoindoloquinazolines.
abstract: The mass spectrometric behavior of stereo- and regioisomeric, partially saturated isoindoloquinazolines was studied by positive-ion electron ionization (EI) and fast-atom bombardment (FAB/LSIMS) mass spectrometry combined with collision-induced dissociation (CID). A highly stereospecific retro-Diels-Alder process was observed in the cyclohexene-fused isomers under the EI conditions, and a corresponding (although less specific) fragmentation was observed in their FAB spectra. In the absence of RDA fragmentations, regio- and stereoisomers of the cyclohexane-fused heterocycles could be distinguished based on their FAB/CID spectra.
authors.affiliation: Structural Chemistry Group, Department of Chemistry, University of Turku, Turku, Finland.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Ovcharenko
authors.forename: Kalevi
authors.initials: K
authors.lastname: Pihlaja
authors.forename: Géza
authors.initials: G
authors.lastname: Stájer