R. Martinez et al., MASS-SPECTRA OF SOME NEW HETEROCYCLES - CYCLOBUTAPYRIMIDINES AND THEIR DIELS-ALDER ADDUCTS WITH C-60, Rapid communications in mass spectrometry, 12(9), 1998, pp. 568-570
The electron impact mass spectra of new compounds, 2,4-dialkyl and 2,4
-diaryl substituted-5,6-dihydrocyclobuta[d]pyrimidines, are reported.
The main fragmentation pathway leads to the formation of cyclobutadien
e [C4H4](+) m/z = 52 as the base peak. The FAB spectra of the adducts
of cyclobutapyrimidines with C-60 have also been recorded. In these sp
ectra the dominant peaks are formed by a retro-Diels-Alder reaction an
d by the apparent loss of the substituents attached at the pyrimidine,
ring forming the ions m/z = 720 and m/z = 825, respectively. (C) 1998
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