Synthesis and antimicrobial activity of certain benzimidazole and fused benzimidazole derivatives

Novel benzimidazole and fused benzimidazole derivatives such as triazinobenzimidazoles 3a-f. oxadia-zolylthiomethyl-1H-benzimidazoles 5a-e. triazolylthiomethyl-1H-benzimidazoles 7a,b, thiazolidinyl-methyl-1H-benzimidazoles 9a-e and pyrimidopyrrolobenzimidazoles 12a,b have been synthesized via several reactions of the key intermediate 2-chloromethyl-1H-benzimidazole with various reagents. Moreover. triazinobenzimidazoles 15a-c have been prepared starting with 2-cyanomethyl-1H-benzimidazole. Finally. another series of oxadiazoles 21a,b and triazoles 23a,b linked to benzimidazole moiety at one position have been synthesized starting with 2-mercapto-1H-benzimidazole. The structures of the newly synthesized compounds have been confirmed on the basis of elemental analysis and spectral studies. Some of the newly synthesized compounds exhibit significant antimicrobial activity, the most active compound is 21a.