Amination, oxidative azines

Even though oxygen in small percentages catalyzes the reaction effectively, many other initiators have been disclosed, including peroxy compounds, ozonides, azo compounds, azines, amine oxides, oximes, hydrazines, and hypohalites. The pol3Tnerization reaction is highly exothermic and requires strict control and elaborate safety measures in order to prevent... 

The aza group activation effect in the oxidative amination of azines is less than that of the nitro group. As an illustration the reaction of 4-nitroquinoline and liquid ammonia in the presence of KMn04 produced 3-amino-4-nitroquinoline only in 86% yield [52]. Oxidative amination of 5-nitroquinoline gave 6-amino derivative in... 

Some azine N-oxides can also be aminated, e.g. (251) — (252). Usually the reaction proceeds better in presence of an oxidant (KMn04, i-PrONO, etc.). 

In the application of oxidation dyes, aromatic amines form insoluble polyazine derivatives in the fiber (azine dyes [81]). Synthesis proceeds in several steps in a hydrochloric acid medium by oxidation (e.g., with dichromate). For the chief representative of this group, aniline black, the chromophore consists of dibenzo-pyran rings. Oxidation dyes are rapidly decreasing in importance because aniline and other aromatic amines as well as the bichromate used for oxidation are toxic. The colors produced by aniline black are characterized by a full bluish black shade and excellent fastness. Since they are easily reserved, they are still used occasionally for printing grounds. For individual processes, see [82],... 

Even poor nucleophiles such as the amides 46 can react with azines in the presence of alkynes as activating agents [59, 60]. Various nucleophiles (including alkoxides, thiols, amines and nitrogen heterocycles) were recently employed in a related process with Ai-oxide azaindoles (Reissert-Henze reaction. Scheme 10). In the process, the oxygen is alkylated with dimethyl sulfate and, after the nucleophilic attack, methanol is released to aromatize the initial adduct [61,62]. Following similar mechanistic trends, V-heteroatom-activated azines afford the corresponding substituted adducts. Likewise, W-tosylated isoquinoline [63, 64] and W-fluoropyridinium salts [65] are also reactive substrates in Reissert-Henze type processes. 

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