Palladium-Catalyzed Enantioselective Cyclopropanation of Unactivated Alkenes with Sulfoxonium Ylides Using a Chiral Monodentate Oxazoline Ligand

The enantioselective cyclopropanation of unactivated alkenes remains a fundamental challenge in synthetic organic chemistry. Herein, we report a palladium-catalyzed, highly enantioselective cyclopropanation of unactivated terminal alkenes with bench-stable sulfoxonium ylides, enabled by a rationally designed chiral monodentate oxazoline (MOX) ligand. This transformation exhibits broad substrate scope and furnishes chiral cis -cyclopropanes in high yields and enantioselectivities (up to 99% yield and 97:3 er). Mechanistic studies reveal that the MOX ligand plays a dual role: it promotes dissociation of the trimeric Pd 3 (OAc) 6 precatalyst into catalytically active monomeric species, thereby facilitating olefin coordination and insertion, and subsequently acts as a transient chiral ligand to control alkene facial selectivity prior to its programmed dissociation. This transient asymmetric induction model provides a unified rationale for the high reactivity and stereocontrol observed.