Dissecting non-covalent interactions in oxazaborolidinium catalyzed cycloadditions of maleimides.

Substrate association and asymmetric induction in oxazaborolidinium-catalyzed cycloadditions of maleimides are shown to depend strongly on the catalyst's aromatic substituents. Favourable dispersive forces bias complexation to the catalyst's convex (exo) face exposing a single diastereoface of the substrate preferentially.