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Mass spectra of some alkyl isoxazoles
Author(s) -
Ohashi Mamoru,
Kamachi Hajime,
Kakisawa Hiroshi,
Tatematsu Akira,
Yoshizumi Hideo,
Kano Hideo,
Nakata Hisao
Publication year - 1969
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.1210020205
Subject(s) - alkyl , mass spectrum , spectral line , chemistry , physics , organic chemistry , ion , astronomy
The mass spectra of several compounds obtained during the process of Stork's isoxazole synthesis9 as well as the related isoxazoles have been investigated. The fragmentations of simple alkyl isoxazoles are nicely formulated via azirine intermediates. A striking difference between the spectra of isoxazoles and those of methylfurans as to the relative abundance of [M — l] peaks is noteworthy. The very low abundance of these peaks in the former reflects the unique character of isoxazole nucleus due to the preferential cleavage of NO linkage rather than a benzylic CH bond rupture. If an alkyl substituent is present at 4‐position in 3,5‐dimethylisoxazoles, strong peaks at m/e 110, 68 and 43 are common in their spectra. The analyses of metastable transitions and high resolution measurements have demonstrated that the formation of these ions can be interpreted by a mechanism involving the cleavage of NO linkage.