Abstract
Mass spectra of benzopyranopyrimidine derivatives and their 4-acetylamino derivatives were measured and their fragmentation mechanisms were elucidated with the aid of the shifts of peaks by the substituent groups and deuterium labeling, and with the aid of the metastable peaks. High resolution mass spectra were also taken for some samples.
Benzopyranopyrimidine derivatives were very stable under electron impact ionization. Fragmentations of benzopyranopyrimidine ring contain characteristic cleavage of both 2-pyrone and pyrimidine ring. And the characteristic cleavage for this structure was also observed. 3,4-Dimethoxy group on the 2-aryl affected the main fragmentation of the benzopyranopyrimidine ring.
Elimination of ketene was the characteristic fragmentation for the 4-acetylamino derivatives.
