From o-Amino Compounds

Oxidative cyclization of o-aminoacylbenzenes is a much less common process for the synthesis of anthranils than the reductive cyclizations discussed in the previous section, mainly because the o-aminoketones are in many instances best prepared by reductive ring opening of anthranils (see Section III,C,3). Nevertheless, a few examples have been recorded. Oxidation of o-aminobenzophenones to the nitroketones using peroxytrifluoro-acetic acid, permaleic acid, or persulfuric acid proceed via the 3-phenyl-anthranil which occasionally is isolable.168 Caro s acid is also a useful oxidant.169 

A novel and highly successful oxidizing agent is phenyl iodosoacetate [PhI(OAc)2]. In benzene solution, this easily prepared reagent oxidizes 2-formyl-, 2-acetyl-, and 2-benzoylaniline to anthranil and its 3-methyl and 3-phenyl derivatives in 21, 71, and 81% yield, respectively.170 Evidence has been accumulated to show that the first stage in the oxidation consists of nucleophilic displacement of acetate followed by neighboring group participation of the acyl function as outlined in Eq. (7). 

In contrast, oxidation of o-aminobenzophenone with lead tetraacetate under a variety of conditions yields only azo compound.171 However, the 

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