Structure/reactivity relationships in the benzo[c]phenanthrene skeleton: stable ion and electrophilic substitution (nitration, bromination) study of substituted analogues, novel carbocations and substituted derivatives.

ABSTRACT: A series of novel carbocations were generated by low-temperature protonation of substituted benzo[c]phenanthrenes, B[c]Phs, and their charge delocalization pathways were elucidated by NMR on the basis of the magnitude of Deltadelta13C values. It has been shown that the protonation regioselectivity is strongly controlled by methoxy and hydroxyl substituents, whose directive effects override methyl substitution effects. Regiocontrol by -OMe and -OH substituents, and its stronger influence relative to methyl groups, was also observed in the nitration and bromination reactions. Charge distribution modes in the regioisomeric protonated carbocations formed via parent B[c]Ph as well as in the benzylic carbocation formed via fjord-region epoxide ring opening were deduced by gauge-invariant atomic

SUBMITTER: Brule C 

PROVIDER: S-EPMC2526040 | biostudies-literature | 2007 Apr

REPOSITORIES: biostudies-literature