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

Article abstract of DOI:10.3987/COM-98-S(H)34

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 medicinal chemistry project was successful only in the case of 6c. Attempted building up of the triazole ring starting from 8-acetylamino-6-chloro-5- nitroquinoline (8) with ammonia, hydrazine and methylhydrazine at 150 °C in ethanol failed. However, the results obtained from these reactions allowed us to observe that, during nucleophilic aromatic substitution of chlorine by these bases an unusual displacement of the nitro group by hydrogen occurred. Comparison of these results with those obtained using different substrates allowed us to evaluate the influence of both para-acetylamino group and pyridine ring in this type of nucleophilic aromatic substitution.