Azaarenes, 2-methyl

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). 

A number of azaarenes have also been detected in cigarette smoke (/7, 28, 56). These have included quinoline, methyl- and dimethylquinolines, isoquinoline, and alkylisoquinolines, benzo[/i]quinoline, acridine, phenan-thridine, benzo[/]quinoline, 4-azafluorenes, 1-azafluoranthenes, 4-azapyrenes, 9-methylcarbazoles, indole, alkylindoles, alkylcarbazoles, benzo[Z>]carbazole, dibenzo[c,g]carbazole, and benz[c]acridine. 

A six-membered hydrogen-bonded transition state apparently enables AcOH-catalysed nucleophilic addition of benzylic C of 2-methyl azaarenes to aldehydes. Tertiary enamides and enecarbamates undergo nucleophilic intramolecular C p2 addition to an iV-CHjCHjCHO group to form 4-hydroxytetrahydropyridine derivatives the enantioselective reaction is promoted by a BINOL-Ti complex. 0... 

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