Azaarene oxides

The halogenoepoxide route to benzene oxides has been used in the synthesis of arene oxides 11, 13, 4116,117 21/ 1 25, and 26 as well as the azaarene oxide 140. The major problem of this synthetic route to non-K-region arene oxides is typified by the results obtained by early attempts to prepare 13 and 15. Thus, the tetrahydroepoxide and bromoepoxide intermediates were highly unstable under the required reaction conditions and yielded a highly impure... 

Cobb, D., Boehlert, C, Lewis, D., and Armstrong, R. N. (1983). Stereoselective of Isozyme C of Glutathione S-lransferase Toward Arene and Azaarene Oxides, Biochemistiy, 22 805-812. 

The oxidation by strains of Pseudomonas putida of the methyl group in arenes containing a hydroxyl group in the para position is, however, carried out by a different mechanism. The initial step is dehydrogenation to a quinone methide followed by hydration (hydroxylation) to the benzyl alcohol (Hopper 1976) (Figure 3.7). The reaction with 4-ethylphenol is partially stereospecific (Mclntire et al. 1984), and the enzymes that catalyze the first two steps are flavocytochromes (Mclntire et al. 1985). The role of formal hydroxylation in the degradation of azaarenes is discussed in the section on oxidoreductases (hydroxylases). 

The oxidative degradations of binuclear azaarenes (quinoline, isoquinoline, and benzodrazines) by hydroxyl and sulfate radicals and halogen radicals have been studied under both photochemical and dark-reaction conditions. A shift from oxidation of the benzene moiety to the pyridine moiety was observed in the quinoline and isoquinoline systems upon changing the reaction from the dark to photochemical conditions. The results were interpreted using frontier-orbital calculations. The reaction of OH with the dye 3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-(l,8)(2//,5//)-acridinedione has been studied, and the transient absorption bands assigned in neutral solution.The redox potential (and also the pA a of the transient species) was determined. Hydroxyl radicals have been found to react with thioanisole via both electron transfer to give radical cations (73%) and OH-adduct formation (23%). The bimolec-ular rate constant was determined (3.5 x lO lmoU s ). " ... 

Fukuhara, K., A. Hakura, N. Sera, H. Tokiwa, and N. Miyata, 1- and 3-Nitro-6-azabenzo[uIpyrenes and Their At-Oxides Highly Mutagenic Nitrated Azaarenes, Chem. Res. Toxicol., 5, 149-153 (1992). 

Arene oxides. Many arenes (and azaarenes) can be converted directly into arene oxides by reaction in an organic solvent with aqueous sodium hypochlorite in the presence of a phase-transfer catalyst such as tetra-n-butylammonium... 

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