Chiral Cages With Asymmetric π-Clefts Enable Catalytic Enantioconvergent S_N1 Transformation via Synergistic Cation-π...

Understanding and exploiting noncovalent interactions are essential for advancing chemical transformations and catalysis. While both cation-π and anion-π interactions have attracted growing attention, their deliberate use as a dominant design element remains elusive. Here, we present an ion-π catalysis strategy employing both π interactions as the key driving force to steer challenging stereoselective carbocation transformation, enabling catalytic enantioconvergent S_N1 reactions. Through straightforward one-pot synthesis, we efficiently constructed a series of chiral cages composed solely of aromatic units, featuring electron-rich asymmetric π clefts and electron-deficient π exterior surfaces. This all-π system leverages strong cation-π interactions to trap and stabilize carbocation intermediates within its chiral V-cleft, while simultaneously engaging the counteranion via anion-π interactions on its exterior surface. This synergistic π network drives a highly enantioconvergent S_N1 process, enabling asymmetric allylation of propargyl acetates to form congested quaternary stereocenters. This system shows considerable sensitivity to subtle electronic and steric changes, resembling enzymatic behavior. This work provides a strategic approach for harnessing noncovalent π interactions to address challenging transformations.