The mass spectrometric behaviour of a series of 2‐aryl substituted 4,7‐dioxo‐4,5,6,7‐tetrahydroindoles has been studied in different ionization conditions (Electron Ionization and Fast Atom Bombardment), with the aid of the metastable ion studies. In electron ionization conditions all the compounds exhibit a highly favoured, primary H2 loss giving rise to the corresponding indole‐4,7‐diones; in the usual spectra no evidence for the molecular ions in the enolic form was found, while the OH* loss observed in the MIKE (mass analyzed ion kinetic energy) spectra of molecular ions suggests that species at low internal energy content isomerize to the corresponding tautomeric enolic form. FAB mass spectra show easy formation of an unusual [M + 2H]+ species, together with abundant [M + H]+ and M+ cations. Copyright © 1993 Journal of Heterocyclic Chemistry
A MASS-SPECTROMETRIC INVESTIGATION ON SOME 4,7-DIOXO-4,5,6,7-TETRAHYDROINDOLE DERIVATIVES
BERTAZZO, ANTONELLA;
1993
Abstract
The mass spectrometric behaviour of a series of 2‐aryl substituted 4,7‐dioxo‐4,5,6,7‐tetrahydroindoles has been studied in different ionization conditions (Electron Ionization and Fast Atom Bombardment), with the aid of the metastable ion studies. In electron ionization conditions all the compounds exhibit a highly favoured, primary H2 loss giving rise to the corresponding indole‐4,7‐diones; in the usual spectra no evidence for the molecular ions in the enolic form was found, while the OH* loss observed in the MIKE (mass analyzed ion kinetic energy) spectra of molecular ions suggests that species at low internal energy content isomerize to the corresponding tautomeric enolic form. FAB mass spectra show easy formation of an unusual [M + 2H]+ species, together with abundant [M + H]+ and M+ cations. Copyright © 1993 Journal of Heterocyclic Chemistry
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