Stereoretentive Nucleophilic Aromatic Substitution Accesses Atropisomeric 4‐Amino‐ N ‐Arylquinolinium Salts

ABSTRACT

We report a novel synthetic route to access N ‐aryl‐4‐amino‐quinolinium salts via a stereoretentive S _N Ar‐type reaction of amines with atropisomeric N ‐arylquinolin‐4‐ones, by in situ formation of the corresponding chloroquinolinium chloride salt. Investigation into the properties of the chiral salts was carried out using x‐ray crystallography, DFT analysis, cyclic voltammetry and UV–vis spectroscopy. They were revealed to possess high rotational barriers (with lifetimes of millennia), new photophysical properties and low oxidation potentials. A neutral axially chiral quinolinimine could be obtained by a simple deprotonation of the quinolinium salt.