Electrophilic Hydroxylation via Oxygen Atom Transfer

In 1950, Derbyshire and Watos first considaed the possibility of electrophilic aromatic hydroxylation with electrophiUc hydroxyl (OH+) [41]. While in gas phase heterolytic cleavage of the 0—0 bond in HjOj molecule requires much more enagy than homolytic cleavage (ca. 300kcal/mol vs. 51 kcal/mol at 298 K), it becomes more favorable in polar solvents in the presence of Lewis or Brpnsted adds [42]. Similarly, peroxy acids (organic or inorganic) can provide electrophilic oxidizing species [42,43]. 

A range of enzymatic and biomimetic systems generate high-valent metal-oxo species, L Fe =0 or LFe =0, one of the most efficient oxygen transfer reagents [44]. 

SCHEME 14.8 Migrations of methyl group in electrophilic hydroxylation of pseudocumene. 

SCHEME 14.9 Proposed mechanism of pseudocumene oxidation with CH ReOj/H O (Reproduced with permission from Ref. [48]. Copyright (2011) Elsevier). 

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