Mass spectrometry of 1,2,5-oxadiazole N-oxide derivatives. Use of deuterated analogues in fragmentation pattern studies

Abstract

This paper reported on the study of fragmentation pattern in mass spectrometry of 1,2,5-oxadiazole N-oxide derivatives involving deuterium-labeled analogues to identify some critical fragmentations. A neutral CH2O loss from 3-hydroxymethyl-N2-oxide-4-phenyl-1,2,5-oxadiazole was confirmed with the corresponding mono-deuterated analogue. An OH loss, involving the oxygen of N-oxide, via β-H and δ5-H rearrangement, was clearly revealed from 3-(4-methylpiperazine-1-ylmethyl)-N2-oxide-4-phenyl-1, 2,5-oxadiazole using the adequate tetra-deuterated analogue. N-oxide isomer and deoxygenated analogues were also used to confirm the participation of the oxide moiety in the fragmentation process.