Electron impact induced fragmentation of aromatic alkoxyimines II [5]. Formation and transformation of heterocyclic radical cations in the gas phase

摘要

The molecular ion 1 of N-(n-propoxy)benzaldimine I rearranges by an 1,5-H-shift to the delta-distonic ion 2 which subsequently cyclizes to the alpha-distonic ion 3. Homolytic cleavage of the N-O bond in 3 results in the delta-distonic ion 4 which expels CH_2O leading to the beta-distonic ion 5. Ion 5 is also formed from the molecular ions of tetrahydrooxazines II and III and from M~(·+) of phenylazeitidine IVa. In a subsequent step, ion 5 cyclizes to the N-protonated 3,4-dihydroisoquinolinium ion 6. The syntheses of II-IV and their derivatives are described.