Oxidative carbonylation arylamines

Electrophilic aromatic substitution of 5-hydroxy-2,4-dimethoxy-3-methylaniline by reaction with the iron complex salts affords the corresponding aryl-substituted tricarbonyliron-cyclohexadiene complexes. O-Acetylation followed by iron-mediated arylamine cydization with concomitant aromatization provides the substituted carbazole derivatives. Oxidation using cerium(IV) ammonium nitrate (CAN) leads to the carbazole-l,4-quinones. Addition of methyllithium at low temperature occurs preferentially at C-1, representing the more reactive carbonyl group, and thus provides in only five steps carbazomycin G (46 % overall yield) and carbazomycin H (7 % overall yield). 

Oxidation. Alcohols and arylamines give carbonyl products and azo compounds, respectively, in MeCN. 

Methods involving rntheninm-catalysed condensations of arylamines with alcohols give indoles the mechanism involves hydride transfer giving aldehyde intermediates. The process can be carried ont intra-molecnlarly or intermolecnlarly, for example by the reaction of aniline with triethanolamine. At a still lower oxidation level, 2-(ort/t(9-aminoaryl)-ethanols can be converted directly into indoles with a catalyst that can oxidise the alcohol to a carbonyl gronp, with expulsion of hydrogen. 

In the Skraup and Doebner-Miller synthesis of quinoline, primary arylamines with an unsubstituted ortho position react with a,p-unsaturated carbonyl compounds in an acid medium in the presence of an oxidizing agent (nitroarene, AS2O5) ... 

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