Of isatogens

Until very recently, most syntheses of isatogens were in this category and characteristically involved ortho-substituted nitrobenzenes. 

Current studies43,44 show that a range of isatogens can now be prepared in good yield by the oxidation of 2-substituted 1-hydroxyindoles and 2-substituted indolines with perbenzoic acids. Until this work, 2-phenylisatogen was reported as only a minor product from a number of reactions of 2-phenylindole derivatives with a variety of oxidizing agents. 

The reduction of indolones is described together with the reduction of isatogens. The major products of reduction are indoxyls and diindoxyls. In some cases the indoxyls are oxidized by air to benzoxazines (Section III,B). Indolones are comparable with isatogens as oxidizing agents88... 

A detailed study of the polarographic reduction of isatogens and indolones has been published.152 The results further substantiate Scheme 10 and Section III,B. 

Preparations of cinnolines by expansion of five-membered heterocycle rings include the oxidation of /V-aminooxindoles (241 — 242), the treatment of isatogens with ammonia (Scheme 30) and the base-catalyzed conversion of 1-aminodioxindoles (243) into cinnolin-3-ones. 

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