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A series of 6-arylbenzimidazo[1,2-c]quinazoline compounds (11-20) were synthesised by the condensation of 2-(o-aminophenyl)benzimidazole with different arylaldehydes, followed by oxidative cyclisation of the resulting 2-o-arylideneaminophenylbenzimidazoles (1-10). All the products were characterized via IR, ¹H NMR, 13C NMR, MS and elemental analysis. The antimicrobial activities of all 6-arylbenzimidazo [1,2-c]quinazolines against three Gram-positive (S. aureus, B. subtilis, S. pyogenes), three Gram-negative (S. typhimurium, E. coli, K. pneumonia) bacteria and three fungal strains (A. niger, C. albicans, T. viridae) were evaluated. Among the compounds tested 13, 19 and 20 showed most potent inhibitory action against test organisms. Uma série de compostos 6-arilbenzimidazo[1,2-c]quinazolina (11-20) foram sintetizados pela condensação do 2-(o-aminofenil)benzimidazol com diferentes arilaldeídos seguida pela ciclização oxidativa dos 2-o-arilidenoaminofenilbenzimidazol (1-10). Todos os produtos foram caracterizados por espectroscopia no infravermelho (IR), ressonância magnética nuclear de prótons e de carbono, (RMN ¹H e RNN 13C), de massas (MS) e análise elementar. A atividade antimicrobial de todos os 6-arilbenzimidazo[1,2-c]quinazolina foi testada com três linhagens de bactérias Gram-positivas (S. aureus, B. subtilis e S. pyogenes), três Gram-negativas (S. typhimurium, E. coli e K. pneumonia) e de três linhagens de fungos (A. niger, C. albicans e T. viridae). Dos compostos testados, o 13, o 19 e o 20 mostraram-se ser os mais potentes inibidores contra os organismos testados.

A convenient three-step strategy is proposed for the synthesis of mono and bis-indolo[1,2-c] quinazolines from 2-(2-aminophenyl)indole and various aryl aldehydes. The newly synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, and mass spectroscopic investigation. All the derivatives were screened for antibacterial (S. aureus, B. subtilis, S. pyogenes, S. typhimurium, E. coli, K. pneumonia) and antifungal (A. niger, C. albicans, T. viridae) activities by cup plate method. Among the compounds tested, mono- indolo[1,2-c] quinazolines (15-18) exhibited good antibacterial activities while 15 and 18 also showed notable antifungal activity. Especially, 19 and 20 exhibited stronger antibacterial as well as antifungal activity against all tested strains.