The ninhydrin core as carbonyl source to access 2-(2′-hydroxyaryl)benzimidazoles exploiting the ortho selectivity of ninhydrin-phenol adducts

Abstract

Although ninhydrin is an essential analytical tool in biochemical and forensic sciences, for the past several years, it has been employed as efficient building block for diverse organic scaffolds. In the present work, the ortho selectivity of ninhydrin-phenol adducts has been exploited to obtain 2-(2′-hydroxyaryl)benzimidazoles which are well known excited state intramolecular proton transfer (ESIPT) fluorophores. Under acidic condition, 3-(2-hydroxyaroyl)isoindolin-1-one intermediate generated in situ from ninhydrin-phenol adducts was treated with o-phenylenediamine resulting benzimidazole scaffolds via a two-step one pot strategy.