Kk. Laali et S. Hollenstein, CHARGE DELOCALIZATION FROM CATIONIC SUBSTITUENTS INTO PHENANTHRENE - VARIATION IN RESPONSE AMONG REGIOISOMERIC CARBOCATIONS AND CARBOXONIUMIONS, Perkin transactions. 2, (4), 1998, pp. 897-904
In an effort to assess charge delocalization and stabilities, a series
of regioisomeric PAH-C+R2 carbocations (PAH = phenanthrene; R = Me, P
h) were generated from their alcohols by ionization with FSO3H/SO2ClF/
Model carboxonium ions were also generated by O-protonation of the is
omeric acetyl- and benzoyl-phenanthrenes with FSO3H/SO2ClF. The deloca
lization paths and the arenium ion character in the resulting carbocat
ions and carboxonium ions are evaluated via low temperature NMR studie
s; conformational aspects in the carboxonium ions are also addressed.
The resulting cations may serve as models for epoxide ring opening in
biologically active dihydro diols of several classes of PAHs for which
the diol epoxide activation path is believed to be significant in can
cer induction.