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Electron ionization fragmentations of some N ‐substituted 2‐ N ‐methylimino‐4,5‐tetramethyleneperhydro‐3, 1‐oxazines and related thiazines
Author(s) -
Pihlaja Kalevi,
LiukkoSipi Sirpa,
Fülöp Ference,
Bernáth Gábor,
Vainiotalo Prijo
Publication year - 1991
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.1290050504
Subject(s) - chemistry , fragmentation (computing) , hydrogen atom , oxazines , ionization , cyclohexane , metastability , electron ionization , mass spectrum , ion , hydrogen , ring (chemistry) , molecule , nitrogen atom , photochemistry , computational chemistry , medicinal chemistry , organic chemistry , alkyl , computer science , operating system
The 70 eV electron ionization mass spectra of six cyclohexane fused 2‐ N ‐methyliminoperhydro‐3,1‐oxazines and six related thiazines were recorded and their fragmentation behaviour studied by metastable‐ion analysis and exact mass measurement. For the unsubstituted compounds, decompositions which can be rationalized to start as a simple α‐cleavages with respect to the ring nitrogen atom were dominant. Many of these reactions were accompanied by a hydrogen‐atom transfer to the neutral fragment lost. N ‐substitution prompted more extensive hydrogen migrations to take place, where hydrogen atoms were transferred to the heterocyclic part of the molecule. Only methyl‐substituted compounds showed remarkable sterochemical specificity, thus allowing isomeric differentiation to take place.