Fragmentation patterns of novel dispirocyclopiperazinium dibromides with strong analgesic activity under electrospray ionization tandem mass spectrometry conditions

Abstract

The fragmentation patterns of a series of dispirocyclopiperazinium dibromides with strong analgesic activity are analyzed by positive ion electrospray ionization mass spectrometry in conjunction with tandem mass spectrometry (ESI-MS(n)). Instead of the parent molecular ions, the fragment ions [M-Br](+) are detected as characteristic double peaks and usually the base peaks. Meanwhile, the fragment ions [M-2Br](2+) are unique for this series of diquaternary ammonium dibromides and show high intensity. Besides the common fragmentation patterns around the carbonyl group, elimination of hydrogen bromide from [M--Br](+) ions is another important pathway. Following the elimination, an interesting rearrangement takes place in the unsaturated spirocyclopiperazine and transforms it into a dihydropyrrole structure, whose fragmentations are similar to its precursor ion in the succeeding steps.

Studies on the metabolism of 4‐methylpiperazine‐1‐carbodithioc acid 3‐cyano‐3,3‐ diphenylpropyl ester hydrochloride in rat bile by high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry

“…To the best of our knowledge, studies of dithiocarbamate derivatives have usually focused on their pharmaceutical activity,2–6 with a few papers reporting their mass spectrometric behavior 7. We have previously determined the mass spectral fragmentation of dispirocyclopiperazinium structures,8, 9 and of some dithiocarbamate derivatives10, 11 synthesized in our laboratory, including TM208, using electrospray ionization multi‐stage mass spectrometry (ESI‐MS n ).…”