Mass spectral fragmentations of mono- and dibenzo-annelated bicyclo[2.2.2]octenes under conditions of electron ionization and chemical ionization

Abstract

The mass spectral fragmentations of one mono- and eight dibenzo-annelated bicyclo[2.2.2]octenes have been studied. Under electron ionization the retro-Diels-Alder (RDA) reaction was dominant and led to the formation of ionized anthracene; only in the case of the monobenzo compound was the RDA + 2 reaction more favourable. Anthracene formation was also important under chemical ionization, but protonation made other fragmentation channels possible so that chemical ionization spectra were strikingly more complicated than electron ionization spectra. © 1997 John Wiley & Sons, Ltd.