Unimolecular decomposition of M+. and [M+H]+ species of some fluorosubstituted acyclic nucleoside analogs.

Electron ionization and fast-atom bombardment mass spectrometry are shown to provide a valid analytical tool for the structural characterization of the title compounds. In fact, diagnostic fragmentation pathways were observed depending on the presence of different substituents (benzyloxy, (benzyloxy, p-tolylthio, p-tolylsulphinyl) as well as of different bases. Regioisomeric compounds could be differentiated by kinetic energy release measurements.