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Differentiation of isomeric 5‐ and 7‐oxo derivatives of tetrahydrothiazolo[3,2‐ a ]pyrimidine by electron impact mass spectrometry
Author(s) -
JeanneauNicolle Edwige,
Bosso Claude,
BenoitGuyod Martine,
Leclerc Gérard
Publication year - 1993
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.1210280109
Subject(s) - electron ionization , mass spectrometry , chemistry , fragmentation (computing) , pyrimidine , mass spectrum , structural isomer , ion , computational chemistry , mass , analytical chemistry (journal) , stereochemistry , chromatography , organic chemistry , ionization , computer science , operating system
The electron impact mass spectra of two series of 5‐oxo‐tetrahydro‐5 H ‐thiazolo [3,2‐ a ]pyrimidine‐6‐ethylcarboxylates and 7‐oxo‐tetrahydro‐7 H ‐thiazolo [3,2‐ a ]pyrimidine‐6‐ethylcarboxylates were measured and fragmentation patterns examined. Structures were assigned from analysis of oxo molecular ion fragmentations. Compounds of the 5‐oxo series gave an [M – CO 2 C 2 H 5 ] + fragmentation whereas compounds of the 7‐oxo series gave three characteristic cleavages. This decomposition was confirmed for one pair of isomers by high‐resolution mass spectrometry and unimolecular mass‐analysed ion kinetic energy spectrometry. Electron impact mass spectrometry is a convenient method for assigning structures of 5‐ and 7‐oxo regioisomers of tetrahydrothiazolo[3,2‐ a ]pyrimidine‐6‐carboxylates.