5-Cyanamino-l,2,4-triazines

It was found that 1,2,4-triazine 4-oxides 55 are active enough to react with cyanamide under basic conditions according to the deoxygenative mechanism to form 5-cyanamino-l,2,4-triazines 73 (00TZV1128). This reaction seems to be facilitated by the easy aromatization of cr -adducts by the Elcb elimination of water. 

When treated with cyanamide in the presence of sodium methoxide 1,2,4-triazine 4-oxides are transformed into 5-cyanamino-l,2,4-triazines (Scheme 48) [106]. Presumably, these basic conditions are favorable for generation of more active nucleophilic species (via the equilibrium formation of NCNH anions), and also they facilitate aromatization of tr -adducts via the Elcb elimination of water. 

An unexpected formation of 2,4-disubstituted-l, 3,5-triazines (3) occurs when 3-dimethoxy-methyl-2-(lV-cyanamino)thiazolidine (2) reacts with secondary amines. When the reaction is carried out in the presence of methanol or ethanol, or with a mixture of amines, a mixture of substituted products is obtained. The proposed mechanism tor the reaction is shown in Scheme 2 [94CC2301]. 

The three monocyclic heteroaromatic 1,2,3,5-triazines 1-3 can be isolated when cyanamide is oxidized electrochemically at a platinum electrode in 2 M potassium hydroxide followed by neutralization with hydrochloric acid or carbon dioxide. The structures of 4-ainino-6-cyanamino-, 4-amino-6-cyanoguanidino- and 4-ureido-6-cyanoguanidino-l,2,3,5-tetrazine (1), (2) and (3), respectively, were confirmed by elemental analysis, IR spectral data and by further transformations.3... 

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See also in sourсe #XX -- [ , ]

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