A study of the electrospray ionisation and ion-trap fragmentation of [M-H](-) ions of new 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazin-2-thione

The electrospray ionisation (ESI) in negative mode of the pharmacologically significant 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazin-2-thiones and their subsequent fragmentations using an ion-trap mass spectrometer, have been investigated. Experiments on sequential product ion fragmentations (MS n) were performed in order to elucidate the degradation pathways for these compounds. The data presented show that the fragmentation of the even-elect ron [M - H](-) ions could proceed through an internal nucleophilic substitu tion displacement. Decarboxylation and extrusion of carbon disulfide are ot her fragmentations observed. Copyright (C) 2001 John Wiley & Sons, Ltd.