Catalytic Enantioselective Synthesis of Axially Chiral Tetraarylethenes.

Chiral TAEs hold great promise for the development of optically active materials. However, current strategies for constructing such structures are largely limited to introduce spatially distal central chirality or intrinsically helical chirality. In this work, we have incorporated axial chirality to create a novel class of skeletally innovative atropisomeric TAEs for the first time. A CPA-catalyzed desymmetrization of prochiral TAEs has been established, enabled by an enantioselective aromatic substitution of phenols using 1,2,4-triazole-3,5-diones as electrophiles. This method achieves excellent efficiency and enantiocontrol for all attempted substrates under the optimized conditions. The resulting highly enantioenriched TAEs enable stereospecific modifications to produce a diverse range of axially chiral TAEs. This work not only complements existing achievements but also provides a rapid and efficient route to access TAE-based chiroptical devices with favorable asymmetry factors and quantum fluorescence efficiency.