Does the electron ionization induced fragmentation of partly saturated stereoisomeric pyrrolo-and isoindoloquinazolinones show stereospecificity?

Kalevi Pihlaja, Olli Martiskainen, G. Stájer

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Abstract

The electron ionization mass spectrometric behavior of pyrroloquinazolinones (1-6) and isoindoloquinazolinones (7-14) was studied. These compounds were further classified as partly saturated pyrroloquinazolinones (1-3), benzologues (7-11), methylene-bridged derivatives (4-6, 12, 13) and a bisacyl compound (14). The mass spectra of the pyrrolo- and isoindoloquinazolinones did not exhibit stereospecific retro-Diels-Alder (RDA) fragmentations. The cyclohexane-fused compounds 7 (cis annelated) and 8 (trans annelated) did display some other ions differing in their abundances that could be used to differentiate this pair of stereoisomers. Also the cyclohexene-fused compounds 2,3, 9 and 10 exhibited somewhat different ion abundances pairwise that could be utilized for isomeric differentiation. Earlier hypothesis of pyrrolo ring cleavage via the loss of C3H5O. was strengthened by the fragmentation of compounds 1-4. RDA(±H) fragmentation is more favorable than the formation of [M-R]+ ions (R=H, C6H4CH3, or C6H4Cl) when an unsaturated bicyclic group is present but both RDA fragmentation and [M-R]+ formation occur for cyclohexene-fused compounds, possibly because of the lower ring strain than with norbornene-fused compounds. The [M-H]+ ion was abundant for compounds 7 and 8 as was [M-Ar] + for 1-4 and 11. Although the compounds studied might participate in amide-imidol tautomerism, no indication of such tautomerism was detected.

Original languageEnglish
Pages (from-to)653-660
Number of pages8
JournalRapid Communications in Mass Spectrometry
Volume21
Issue number5
DOIs
Publication statusPublished - 2007

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Ionization
Ions
Electrons
Stereoisomerism
Amides
Derivatives
cyclohexene

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy

Cite this

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title = "Does the electron ionization induced fragmentation of partly saturated stereoisomeric pyrrolo-and isoindoloquinazolinones show stereospecificity?",
abstract = "The electron ionization mass spectrometric behavior of pyrroloquinazolinones (1-6) and isoindoloquinazolinones (7-14) was studied. These compounds were further classified as partly saturated pyrroloquinazolinones (1-3), benzologues (7-11), methylene-bridged derivatives (4-6, 12, 13) and a bisacyl compound (14). The mass spectra of the pyrrolo- and isoindoloquinazolinones did not exhibit stereospecific retro-Diels-Alder (RDA) fragmentations. The cyclohexane-fused compounds 7 (cis annelated) and 8 (trans annelated) did display some other ions differing in their abundances that could be used to differentiate this pair of stereoisomers. Also the cyclohexene-fused compounds 2,3, 9 and 10 exhibited somewhat different ion abundances pairwise that could be utilized for isomeric differentiation. Earlier hypothesis of pyrrolo ring cleavage via the loss of C3H5O. was strengthened by the fragmentation of compounds 1-4. RDA(±H) fragmentation is more favorable than the formation of [M-R]+ ions (R=H, C6H4CH3, or C6H4Cl) when an unsaturated bicyclic group is present but both RDA fragmentation and [M-R]+ formation occur for cyclohexene-fused compounds, possibly because of the lower ring strain than with norbornene-fused compounds. The [M-H]+ ion was abundant for compounds 7 and 8 as was [M-Ar] + for 1-4 and 11. Although the compounds studied might participate in amide-imidol tautomerism, no indication of such tautomerism was detected.",
author = "Kalevi Pihlaja and Olli Martiskainen and G. St{\'a}jer",
year = "2007",
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journal = "Rapid Communications in Mass Spectrometry",
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T1 - Does the electron ionization induced fragmentation of partly saturated stereoisomeric pyrrolo-and isoindoloquinazolinones show stereospecificity?

AU - Pihlaja, Kalevi

AU - Martiskainen, Olli

AU - Stájer, G.

PY - 2007

Y1 - 2007

N2 - The electron ionization mass spectrometric behavior of pyrroloquinazolinones (1-6) and isoindoloquinazolinones (7-14) was studied. These compounds were further classified as partly saturated pyrroloquinazolinones (1-3), benzologues (7-11), methylene-bridged derivatives (4-6, 12, 13) and a bisacyl compound (14). The mass spectra of the pyrrolo- and isoindoloquinazolinones did not exhibit stereospecific retro-Diels-Alder (RDA) fragmentations. The cyclohexane-fused compounds 7 (cis annelated) and 8 (trans annelated) did display some other ions differing in their abundances that could be used to differentiate this pair of stereoisomers. Also the cyclohexene-fused compounds 2,3, 9 and 10 exhibited somewhat different ion abundances pairwise that could be utilized for isomeric differentiation. Earlier hypothesis of pyrrolo ring cleavage via the loss of C3H5O. was strengthened by the fragmentation of compounds 1-4. RDA(±H) fragmentation is more favorable than the formation of [M-R]+ ions (R=H, C6H4CH3, or C6H4Cl) when an unsaturated bicyclic group is present but both RDA fragmentation and [M-R]+ formation occur for cyclohexene-fused compounds, possibly because of the lower ring strain than with norbornene-fused compounds. The [M-H]+ ion was abundant for compounds 7 and 8 as was [M-Ar] + for 1-4 and 11. Although the compounds studied might participate in amide-imidol tautomerism, no indication of such tautomerism was detected.

AB - The electron ionization mass spectrometric behavior of pyrroloquinazolinones (1-6) and isoindoloquinazolinones (7-14) was studied. These compounds were further classified as partly saturated pyrroloquinazolinones (1-3), benzologues (7-11), methylene-bridged derivatives (4-6, 12, 13) and a bisacyl compound (14). The mass spectra of the pyrrolo- and isoindoloquinazolinones did not exhibit stereospecific retro-Diels-Alder (RDA) fragmentations. The cyclohexane-fused compounds 7 (cis annelated) and 8 (trans annelated) did display some other ions differing in their abundances that could be used to differentiate this pair of stereoisomers. Also the cyclohexene-fused compounds 2,3, 9 and 10 exhibited somewhat different ion abundances pairwise that could be utilized for isomeric differentiation. Earlier hypothesis of pyrrolo ring cleavage via the loss of C3H5O. was strengthened by the fragmentation of compounds 1-4. RDA(±H) fragmentation is more favorable than the formation of [M-R]+ ions (R=H, C6H4CH3, or C6H4Cl) when an unsaturated bicyclic group is present but both RDA fragmentation and [M-R]+ formation occur for cyclohexene-fused compounds, possibly because of the lower ring strain than with norbornene-fused compounds. The [M-H]+ ion was abundant for compounds 7 and 8 as was [M-Ar] + for 1-4 and 11. Although the compounds studied might participate in amide-imidol tautomerism, no indication of such tautomerism was detected.

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SN - 0951-4198

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