Dihetarylethene photocyclization as a synthetic route to fluorescent compounds

[Display omitted] •Imidazol-2-ones were prepared by three-component condensation.•Synthesis of polycyclic compounds by photocyclization.•Photochemically generated polycyclic products possess intense fluorescence. It was shown that UV irradiation of imidazoline-bridged dihetarylethenes affords fused products exhibiting fluorescence. The starting compounds were prepared by three-component condensation of N,N’-dimethylurea with arylglyoxals and enols. A method was proposed for the synthesis of polycyclic imidazole derivatives by photoinduced cyclization followed by elimination of a water molecule. The advantages of the method include readily accessible starting compounds, process simplicity, and the ease of isolation of the target products. The crystal structure of the cyclization products was determined. It was shown that unlike the starting imidazol-2-ones, all photochemically prepared polycyclic products exhibit intense fluorescence.