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Electron ionization mass spectral studies of bridgehead‐substituted norbornan‐2‐ones: camphor derivatives
Author(s) -
Teso Vilar Enrique,
Fraile Amelia García,
Cerero Santiago de la Moya,
MartínezRuiz Paloma,
Jiménez Florencio Moreno
Publication year - 2011
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4839
Subject(s) - chemistry , substituent , fragmentation (computing) , electron ionization , mass spectrum , ionization , ion , dissociation (chemistry) , computational chemistry , mass spectrometry , stereochemistry , organic chemistry , chromatography , computer science , operating system
The electron ionization (EI) mass spectra of a series of bridgehead‐substituted 3,3‐dimethylnorbornan‐2‐ones, derived from natural (1 R )‐(+)‐camphor, have been studied and their cleavage mechanisms rationalized on the basis of the substituent shifts as well as on the identification of relevant peaks through accurate mass measurements and collision‐induced dissociation (CID) tandem mass spectrometric experiments. The fragmentation patterns are very dependent on both the structural nature and the electronic properties of the bridgehead substituent. The driving force for the main fragmentation pathways are competitive cleavages of the C(1)–C(2) and C(2)–C(3) bonds directed by the bridgehead substituent and either the gem ‐dimethyl or carbonyl groups. These cleavages lead to distonic ions in which the charge is preferentially located either at the C(1), C(2) or C(3) positions depending on the electronic character and structural nature of the bridgehead substituent. This charge distribution determines the subsequent rearrangements and fragmentations. Copyright © 2011 John Wiley & Sons, Ltd.