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Benzylic cleavage and McLafferty rearrangement under electron ionization conditions in the fragmentation of 5,6-dialkyl-2,4-diarylpyrimidines

✍ Scribed by R. Martínez Alvarez; A. Herrera Fernández; M. Chioua; P. Ramiro Pérez; N. Villalba Vilchez; F. Guzmán Torres

Publisher
John Wiley and Sons
Year
1999
Tongue
English
Weight
138 KB
Volume
13
Category
Article
ISSN
0951-4198

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✦ Synopsis

Several 5,6-dialkyl-2,4-diarylpyrimidines were prepared and their electron ionization (EI) mass spectra reported. The benzylic cleavage takes place easily together with an important McLafferty rearrangement. The involvement of the nitrogen atom appears to be important in the fragmentation of 5-methyl-substituted pyrimidines. In contrast, the 6-methyl-substituted pyrimidines undergo benzylic cleavage without hydrogen transfer. Thus, the difference in the mass spectrometric behaviour allows the identification of these isomeric compounds which, in contrast, exhibit only small differences in their NMR spectra.

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