Aromatization of arene oxides

Substituent effects upon the rates of aromatization of arene oxides, both by the acid-catalyzed and spontaneous pathways, gave large negative p values (—5.5 to —5.0) indicative of transition states possessing significant carbonium ion character. ... 

The importance of carbonium ion intermediates during aromatization of arene oxides has also been deduced from the migration and loss of a range of arene-oxide substituents. Aromatization of polymethylated arene oxides, for example, 61, 63, and 65, ° in each case yielded phenols where methyl migration occurred. Related arene 1,2-oxides have been extensively studied since their aromatization may involve both substituent loss and/or migration. 

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