Gas-Phase Reactivities and Interchromophoric Effects in 1,n -Dicarbazolylalkane Cations and Related Species
Journal of Organic Chemistry
The behavior of gaseous cations derived from electron ionization (20 and 70 eV) and methane chemical ionization (CI) of 1,n-dicarbazolylalkanes la-5a (where n = 1-5 methylene units, respectively) and the corresponding 3-nitro derivatives lb-Sb was examined using mass spectrometry. An iminium ion (mlz 180) is the major fragment from all 1-5 examined with the exception of 4a, for which CI affords predominantly a pyrrolidinium ion (m/z 222) by displacement of carbazole. Compounds la and lb exhibit little [MI'+ and [M + H]+ and undergo the most extensive fragmentation. Ethylated iminium ion (mlz 208) is observed from both la and lb under CI conditions, indicating operation of an interannular hydrogen shift. Compound 3a fragments least, consistent with an exceptional, although small, stabilization for the parent ions of this derivative.
Schildcrout, S. M.; Krafcik, R. B.; Masnovi, J. Gas-phase reactivities and interchromophoric effects in 1,n-dicarbazolylalkane cations and related species. J. Org. Chem. 1991, 56, 7026-7034.