Photochemical generation of highly destabilized vinyl cations: the effects of alpha- and beta-trifluoromethyl versus alpha- and beta-methyl substituents.

The photochemical reactions in methanol of the vinylic halides 1-4, halostyrenes with a methyl or a trifluoromethyl substituent at the alpha- or beta-position, have been investigated quantitatively. Next to E/Z isomerization, the reactions are formation of vinyl radicals, leading to reductive dehalogenation products, and formation of vinyl cations, leading to elimination, nucleophilic substitution, and rearrangement products. The vinyl cations are parts of tight ion pairs with halide as the counterion.

Fluorobenzo[a]pyrenes as probes of the mechanism of cytochrome P450-catalyzed oxygen transfer in aromatic oxygenations.

Fluoro substitution of benzo[a]pyrene (BP) has been very useful in determining the mechanism of cytochrome P450-catalyzed oxygen transfer in the formation of 6-hydroxyBP (6-OHBP) and its resulting BP 1,6-, 3,6-, and 6,12-diones. We report here the metabolism of 1-FBP and 3-FBP, and PM3 calculations of charge densities and bond orders in the neutral molecules and radical cations of BP, 1-FBP, 3-FBP, and 6-FBP, to determine the mechanism of oxygen transfer for the formation of BP metabolites. 1-FBP and 3-FBP were metabolized by rat liver microsomes.