Fragmentation of dihydro- and tetrahydro-1,5-benzothiazepines under electron impact

The fragmentation mechanisms of dihydro- and tetrahydro-1,5-benzothiazepines under electron impact have been studied in detail using high resolution mass spectrometry, metastable decompositions and deuterium labelling techniques. Both kinds of the benzothiazepines possess high stability. The M? SH]⁺ and the cyclic benzothiazole ions derived from the fragmentation and severe skeletal rearrangement of the molecular ion comprised the main features of the spectra. Some doubly charged ions were noticed in the low resolution electron impact mass spectra.