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Mass spectrometry of modified nucleic acid bases and nucleosides. 2. Class II mesoionic nucleosides and bases derived from thiazolo[3,2‐ a ]pyrimidine‐5,7‐diones
Author(s) -
Schubert Ernst M.,
Schram Karl H.,
Glen Richard A.
Publication year - 1985
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570220357
Subject(s) - mesoionic , chemistry , pyrimidine , mass spectrum , nucleoside , mass spectrometry , fast atom bombardment , fragmentation (computing) , mass , stereochemistry , ion , computational chemistry , organic chemistry , chromatography , computer science , operating system
The mass spectral characteristics of novel Class II mesoionic heterocyclic bases and nucleosides based on the thiazolo[3,2‐ a ]pyrimidine‐5,7‐dione system have been examined using low and high resolution mass spectrometry and metastable ion analysis. The mass spectra of these Class II mesoionic nucleosides differ significantly from the spectra of “normal” nucleosides by the absence of fragment ions associated with the base plus portions of the sugar. The difference in fragmentation is rationalized on the basis of exclusive localization of the radical‐charge site in the aglycone, a result of the mesoionic structure of these molecules. The fast atom bombardment (FAB) mass spectra of a Class I mesoionic nucleoside, 7‐methylguanosine, is compared to the FAB mass spectra of the Class II mesoionic nucleosides.