Synthesis and Characterization of Nucleoside Analogues via Mannich Reaction of Benzimidazole and Their Biological Activity

New nucleoside analogues have been synthesized through the Mannich reaction starting from 4-methoxybenzaldehyde and α-D-mannose. The aromatic aldehyde was condensed with o-phenylene diamine to obtain 2-(4-methoxyphenyl)-1H-benzimidazole, and the subsequent Mannich reaction with protected α-D-mannofuranosyl bromide afforded new protected nucleoside analogues. Hydrolysis of the latter with sodium methoxide in methanol gave the target free nucleoside analogues. The synthesized compounds were identified by FT-IR and ¹H and ¹³C NMR spectroscopy, and their in vitro antibacterial activity against four bacterial and fungal strains was evaluated.