The gas-phase amino–claisen rearrangement of protonated N-allylaniline

Metastable molecular protonated ions of N-allylaniline dissociate with significant losses of ethene and ammonia in the flight path of a mass spectrometer. The structures of the daughter ions formed on the loss of ethene have been elucidated using collision-induced dissociation and it is postulated that two isomeric structures are formed, one corresponding to molecular protonated ions which have undergone an amino–Claisen rearrangement. The relative proportion of this rearranged species is dependent on the exothermicity of the proton-transfer reaction between the sample molecule and the chemical ionization reagent gas ion. It is proposed that the two isomeric parent species differ in the site of protonation.