Fragmentation and intramolecular cyclization in cyclopentane‐4,5‐fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and related thiazines under electron impact ionization

Pentti Oksman, Kalevi Pihlaja, Ferenc Fülöp, Gábor Bernáth

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7 Citations (Scopus)

Abstract

The influence of cyclopentane fusion on the fragmentation behaviour of 1,3‐oxazines and related thiazines was studied. The differences observed in the rearrangement reactions between the hydrogen atom at the ortho position of the aromatic ring and one of the hetero atoms in the cyclohexane ring were also investigated. These rearrangements occur if the cyclohexane ring contains an electrophilic atom and the carbon atom next to it is substituted by a benzyl or arylamino group. The compounds examined were cis and trans isomers of the title compounds substituted with methyl and benzyl (in the latter case only the cis isomers) on the ring nitrogen. All the compounds exhibited a large [M  H]+ ion peak which decreased with increasing size of the substituent. This indicates an intramolecular cyclization prior to further fragmentation of the molecule. Methyl substitution seems to change the character of this intramolecular cyclization. The main routes of fragmentation resemble those of the cyclohexane‐fused analogues more than those of the corresponding 5,6‐fused compounds. The stereoisomers fragment so similarly that they cannot be distinguished from each other, except in the case of methyl substituted oxazines.

Original languageEnglish
Pages (from-to)615-624
Number of pages10
JournalRapid Communications in Mass Spectrometry
Volume9
Issue number7
DOIs
Publication statusPublished - Jan 1 1995

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Thiazines
Impact ionization
Cyclization
Atoms
Electrons
Isomers
Oxazines
Cyclopentanes
Stereoisomerism
Hydrogen
Substitution reactions
Nitrogen
Fusion reactions
Carbon
Ions
Molecules

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry

Cite this

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title = "Fragmentation and intramolecular cyclization in cyclopentane‐4,5‐fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and related thiazines under electron impact ionization",
abstract = "The influence of cyclopentane fusion on the fragmentation behaviour of 1,3‐oxazines and related thiazines was studied. The differences observed in the rearrangement reactions between the hydrogen atom at the ortho position of the aromatic ring and one of the hetero atoms in the cyclohexane ring were also investigated. These rearrangements occur if the cyclohexane ring contains an electrophilic atom and the carbon atom next to it is substituted by a benzyl or arylamino group. The compounds examined were cis and trans isomers of the title compounds substituted with methyl and benzyl (in the latter case only the cis isomers) on the ring nitrogen. All the compounds exhibited a large [M  H]+ ion peak which decreased with increasing size of the substituent. This indicates an intramolecular cyclization prior to further fragmentation of the molecule. Methyl substitution seems to change the character of this intramolecular cyclization. The main routes of fragmentation resemble those of the cyclohexane‐fused analogues more than those of the corresponding 5,6‐fused compounds. The stereoisomers fragment so similarly that they cannot be distinguished from each other, except in the case of methyl substituted oxazines.",
author = "Pentti Oksman and Kalevi Pihlaja and Ferenc F{\"u}l{\"o}p and G{\'a}bor Bern{\'a}th",
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T1 - Fragmentation and intramolecular cyclization in cyclopentane‐4,5‐fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and related thiazines under electron impact ionization

AU - Oksman, Pentti

AU - Pihlaja, Kalevi

AU - Fülöp, Ferenc

AU - Bernáth, Gábor

PY - 1995/1/1

Y1 - 1995/1/1

N2 - The influence of cyclopentane fusion on the fragmentation behaviour of 1,3‐oxazines and related thiazines was studied. The differences observed in the rearrangement reactions between the hydrogen atom at the ortho position of the aromatic ring and one of the hetero atoms in the cyclohexane ring were also investigated. These rearrangements occur if the cyclohexane ring contains an electrophilic atom and the carbon atom next to it is substituted by a benzyl or arylamino group. The compounds examined were cis and trans isomers of the title compounds substituted with methyl and benzyl (in the latter case only the cis isomers) on the ring nitrogen. All the compounds exhibited a large [M  H]+ ion peak which decreased with increasing size of the substituent. This indicates an intramolecular cyclization prior to further fragmentation of the molecule. Methyl substitution seems to change the character of this intramolecular cyclization. The main routes of fragmentation resemble those of the cyclohexane‐fused analogues more than those of the corresponding 5,6‐fused compounds. The stereoisomers fragment so similarly that they cannot be distinguished from each other, except in the case of methyl substituted oxazines.

AB - The influence of cyclopentane fusion on the fragmentation behaviour of 1,3‐oxazines and related thiazines was studied. The differences observed in the rearrangement reactions between the hydrogen atom at the ortho position of the aromatic ring and one of the hetero atoms in the cyclohexane ring were also investigated. These rearrangements occur if the cyclohexane ring contains an electrophilic atom and the carbon atom next to it is substituted by a benzyl or arylamino group. The compounds examined were cis and trans isomers of the title compounds substituted with methyl and benzyl (in the latter case only the cis isomers) on the ring nitrogen. All the compounds exhibited a large [M  H]+ ion peak which decreased with increasing size of the substituent. This indicates an intramolecular cyclization prior to further fragmentation of the molecule. Methyl substitution seems to change the character of this intramolecular cyclization. The main routes of fragmentation resemble those of the cyclohexane‐fused analogues more than those of the corresponding 5,6‐fused compounds. The stereoisomers fragment so similarly that they cannot be distinguished from each other, except in the case of methyl substituted oxazines.

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