Isomérisation de l'ion phényl-2 oxétane protoné avant sa fragmentation en spectrométrie de masse

Fragmentations of the phenyl-2 oxetane ion by chemical ionization mass spectrometry, and of some isomeric ions, have been studied using deuterated and 13C labelled compounds. The heterocyclic system of the protonated phenyl-2 oxetane ion is broken before fragmentation giving a hydroxylated carbocation which can isomerize by 1–2 or 1–3 hydride transfers. The protonated phenyl-3 propanal thus obtained eliminates a molecule of water and yields a protonated indene ion. The potential energy profile and the mechanism proposed are in agreement with the experimental results.