Atroposelective Synthesis, Structure and Properties of a Novel Class of Axially Chiral N-Aryl Quinolinium Salt

Abstract

Inspired by naturally occurring molecules containing atropisomeric N+-C axes, we have developed a novel synthetic approach to generate a library of axially chiral N-aryl quinolinium salts. Enantiopurities up to 93 % ee were obtained via a four-step route from commercially available precursors. Axial stereochemistry was controlled through an enantioselective ring-closing Buchwald–Hartwig coupling reaction. The structure and properties of the salts were examined by X-ray crystallography, DFT, UV-Vis, and fluorescence spectroscopy, revealing high rotational barriers and solvatochromic behaviour.