Synthesis of triazolo[4,5-f]quinolines. An unusual case of displacement ofnitro group in the reaction of 8-acetylamino-6-chloro-5-nitroquinoline with hydrazine and methylhydrazine

Nitration of 1H-, 3-methyl- and 2-methyltriazolo[4,5-f]quinolines (6a-c) as a way to obtain the desired 4-aminotriazolo[4,5-f]quinolines (4) for a med icinal chemistry project was successful only in the case of 6c. Attempted b uilding up of the triazole ring starting from 8-acetylamino-6-chloro-5-nitr oquinoline (8) with ammonia, hydrazine and methylhydrazine at 150 degrees C in ethanol failed, However, the results obtained from these reactions allo wed us to observe that, during nucleophilic aromatic substitution of chlori ne by these bases an unusual displacement of the nitro group by hydrogen oc curred. Comparison of these results with those obtained using different sub strates allowed us to evaluate the influence of both para-acetylamino group and pyridine ring in this type of nucleophilic aromatic substitution.