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Ring contraction upon electron‐impact as a function of ring size: The mass spectrometric fragmentation of 2,3,4,5‐tetrahydrobenzoxepin and lower homologues
Author(s) -
Richter W. J.,
Liehr J. G.,
Burlingame A. L.
Publication year - 1973
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210070412
Subject(s) - fragmentation (computing) , chemistry , deuterium , mass spectrum , electron ionization , polyatomic ion , methylene , ion , contraction (grammar) , ring size , molecule , ring (chemistry) , labelling , stereochemistry , medicinal chemistry , organic chemistry , physics , atomic physics , medicine , ionization , operating system , biochemistry , computer science
The origin of a prominent [M – CH 3 ] ion in the mass spectrum of 2,3,4,5‐tetrahydrobenzoxepin is investigated with the aid of extensive deuterium labelling of the saturated heterocyclic portion of the molecule, identifying the C‐2 methylene group as the chief source of the methyl radical expelled. Ring contraction of the seven‐membered cyclic molecular ion to a six‐membered intermediate is proposed in accordance with interpretations of similar findings on related acylated cyclic amines.