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Is the atmospheric pressure chemical ionisation and collisionally induced methanol loss from protonated dehydroamino acids a retrosynthetic process?
Author(s) -
Tubaro Michela,
Fedrigo Maria Anna,
Cativiela Carlos,
Jiménez Ana Isabel,
Traldi Pietro
Publication year - 2002
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.879
Subject(s) - chemistry , protonation , atmospheric pressure chemical ionization , methanol , molecule , ion , deuterium , retrosynthetic analysis , mass spectrometry , ionization , formic acid , computational chemistry , photochemistry , chemical ionization , organic chemistry , chromatography , atomic physics , physics , total synthesis
Unsaturated 5(4 H )‐oxazolones lead, by methanolysis, to the corresponding dehydroamino acid derivatives. Interestingly, under atmospheric pressure chemical ionisation (APCI) conditions, the latter give rise, aside from abundant [M+H] + ions, to [MHCH 3 OH] + species, formally corresponding to the protonated oxazolones employed for their synthesis. Retrosynthetic processes have often been described as energetically favoured decompositions of odd‐electron molecular ions but never invoked in APCI‐activated fragmentations. To investigate this possible retrosynthetic process, occurring also under collisional conditions, some experiments on the deuterated analogues have been undertaken. The breakdown curves of [M+H] + of oxazolones and [MHCH 3 OH] + of the dehydroamino acid derivatives are superimposable, proving their structural identity and giving experimental evidence of the occurrence of a real retrosynthetic process from even‐electron protonated molecules. Copyright © 2002 John Wiley & Sons, Ltd.