On the Oxidation of Bridged 1‐Naphthylamine and Aniline Derivatives – Formation of Substituted Quinoline and Benzo[ c , d ]indole Derivatives

The bridged aniline or 1‐naphthylamine derivatives 8–10 react with nitrous acid in the presence of perchloric acid to give the bridged diphenoquinone diiminium salts 12 ·2 HClO 4 , 17 ·2 HClO 4 , 19 ·2 HClO 4 and 23 . The same products are obtained from these substrates upon their reaction with hydrogen peroxide. Upon treatment of the bridged diphenoquinone diiminium salts 12 ·2 HClO 4 and 23 with base, a disproportionation reaction occurs resulting in the formation of the corresponding benzidine derivatives 13 and 26 and, following a multistep process, the quinoline derivatives 15 and 25 are obtained. Analogously, the 1,2‐dihydrobenzo[ c,d ]indole hydroperchlorate 10 ·HClO 4 is transformed into the bridged benzidine derivative 21 and the bis(benzo[ c,d ]indol‐6‐yl) hydroperchlorate 20 ·HClO 4 . Furthermore, as a result of an oxidation process initiated by the protonated species of the corresponding indaminium salts, condensation of N , N ‐dimethyl‐4‐nitrosoaniline ( 27 ) with the bridged aniline or naphthylamine derivatives 8a–8c leads to the N ′‐(6‐quinolyl)‐substituted N , N ‐dimethylbenzoquinone bis(iminium) salts 29a–28c rather than the corresponding indaminium salts 28a–28c .