Reusable shuttles for exchangeable functional cargos: Reversibly assembled, magnetically powered organocatalysts for asymmetric aldol reactions

A supramolecular approach has been followed to support adamantyl substituted proline organocatalysts onto the surface of magnetite nanoparticles decorated with a β-cyclodextrin motif. The resulting magnetic nanoparticles (ca. ∼10 nm diameter) were used as modular, magnetically recyclable catalysts in the asymmetric aldol reaction of aromatic aldehydes with cyclic ketones in water. The catalytic assemblies can be easily dismantled in organic media, and the recovered nanoparticles (magnetically powered chemical shuttles) re-complexed with another suitably substituted catalytic unit (replaceable functional cargo).