A Novel 1,3‐Sigmatropic Rearrangement in an Iminium Ion Generated in Collision‐Induced Decomposition During Electrospray Ionization High Resolution Multistage Mass Spectrometry

Elucidation of such an intra-molecular rearrangement mechanism not only enriches our understanding of the gas phase dissociation chemistry, but also should facilitate future rapid structural characterization of unknown pharmaceutical impurities and metabolites using multistage mass spectrometric analysis.