π-Stacking interactions at the service of [Cu]-bis(oxazoline) recycling

Anthracene- and pyrene-tagged bis(oxazoline) ligands have been prepared and immobilized on charcoal, fullerene, and single-walled carbon nanotubes through π-π interactions. The corresponding copper complexes have been evaluated for their propensity to promote heterogeneous asymmetric Henry and ene reactions. The best results, in terms of activity, selectivity, and stability toward the recycling procedure have been obtained with the pyrene/SWCNT system, as the first example demonstrating the usefulness of such reversible interactions for the asymmetric formation of new C-C bonds.