Directional Approach to Enantiomerically Enriched Functionalized [7]Oxa-helicenoids and Groove-Based Selective Cyanide Sensing

Several regioselective functionalized mono- and disubstituted [7]­oxa-helicenoids have been synthesized in the enantiomerically enriched (90–99% ee) form. These functionalized helicenoids exhibited pronounced spectral and chiroptical properties suitable for sensing applications. In particular, corresponding helicenoid’s mono and dialdehydes have been effectively used as chemodosimeters for selective detection of cyanide anions over other anions, while simple aromatic aldehydes do not function as cyanide sensors. The groove available in the helical host plays a crucial role in the sensing. The enantiomerically enriched nature of the sensors allows the use of electronic circular dichroism as an uncommon detection tool for cyanide anions, along with conventional fluorescence and NMR methods.