Loss of hydroxyl radical from cis- and trans-1-cyclohexyl 2-phenyl-3-benzoylaziridines: A unique eight-centered rearrangement elimination

Following electron impact ionization of the title compounds, a rapid electrocyclic ring opening of the M]⁺˙ of both isomers occurs. A subsequent fragmentation of each is loss of hydroxyl which occurs by rearrangement to the carbonyl function. Properties of M? OH]⁺ are in accord with a stable structure for this ion and therefore it is assigned as the 4-phenylisoquinium ion. The proposed mechanism and ion structures are supported by deuterium labeling and defocused metastable ion studies.