Enantioselective Synthesis of Atropisomeric Biaryl Phosphorus Compounds by Chiral Phosphonium-Salt-Enabled Cascade Arene Formation.

Axially chiral biaryl monophosphorus molecules, exemplified by atropisomeric 1,1'-biaryl aminophosphines, are significant motifs in numerous chiral ligands/catalysts. Developing efficient methods for preparing phosphorus compounds with these privileged motifs is an important endeavor in synthetic chemistry. Herein, we develop an effective, modular method by chiral phosphonium salt-catalyzed novel cascade between phosphorus-containing nitroolefins and α,α-dicyanoolefins, leading to a great diversity of atropisomeric biaryls bearing phosphorus groups in high yields with excellent stereoselectivities. The reaction features include a Thorpe-type cycloaddition/oxidative hydroxylation/aromatization cascade pathway with a central-to-axial chirality transfer process. Insights gained from our studies are expected to advance general efforts towards the catalytic synthesis of atropisomeric biaryl phosphorus compounds, offering platform for developing new efficient chiral ligands and catalysts.