Design, microwave-assisted synthesis, and spasmolytic activity of 2-(alkyloxyaryl)-1H-benzimidazole derivatives as constrained stilbene bioisosteres

A simple, fast, and efficient method for the preparation of several 2-(alkyloxyaryl)-1H-benzimidazole derivatives is reported. Compounds were synthesized through a rapid one-pot three component reaction via microwave irradiation, starting from commercially available aldehydes and o-phenylenediamine, in the presence of Na2S2O5 and solvent-free conditions. The design of these compounds explore the hypothesis that the stilbene framework could be mimicked with an appropriate 2-(Alkyloxyphenyl)benzimidazole scaffold. This framework has a similar structural motif as the 6-phenylnaphthalene and behaves like stilbene bioisosteres. The spasmolytic activity of these compounds was recorded using isolated rat ileum test. Compound 12 was the most active of the series, showing an IC50 of 1.19 μM.