Construction of axial chirality via palladium/chiral norbornene cooperative catalysis

Abstract

Axially chiral biaryls are common structural motifs in functional materials, bioactive natural products, pharmaceuticals and chiral catalysts/ligands. As such, efficient preparation of these privileged scaffolds is an important endeavour in organic chemistry. Herein we report a general and modular platform technology for the construction of axial chirality via palladium/chiral norbornene cooperative catalysis. It is a three-component cascade process that involves widely available aryl iodides, 2,6-substituted aryl bromides and olefins (or alkynes, boronic acids and so on) as the reactants. A wide variety of substrates bearing an assortment of functional groups (88 examples) are compatible with this method. Other features include a distinct stereoinduction model, excellent enantioselectivities, step economy and scalability. This method is also amenable for the synthesis of chiral fluorenols through axial-to-central chirality transfer in high stereochemical fidelity. We anticipate that this work will have broad synthetic utilities in chiral ligands and catalyst-design for asymmetric catalysis. Axial chirality is found in many important compounds, such as bioactive molecules and catalytic components. Now palladium and chiral norbornene cooperative catalysis is reported for the construction of atropisomeric biaryls and chiral fluorenols.