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 a 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.