Ligand-Controlled Divergent Enantioselective Hydroarylation of Cyclobutenes

Abstract

The palladium-catalyzed enantioselective redox-neutral coupling of alkenes with organoboronic reagents remains an unfulfilled challenge. Herein, we report a divergent palladium-catalyzed enantioselective hydroarylation of cyclobutenes with arylboronic acids, affording both 1,2- and 1,3-hydroarylation products. The regioselectivity was tuned by judicious choice of chiral ligands. The palladium-hydride species was generated from palladium catalyst and arylboronic acid or in situ generated HOAc, as supported by deuterated experiments and density functional theory (DFT) calculations. We anticipate that this redox-neutral coupling with organoboronic reagents could stimulate interest in other unsaturated alkene systems.