Noncovalent Immobilization of Enantioselective Catalysts

Various methods of immobilization applied to enantioselective catalysts that do not require the covalent link of the chiral ligand to a solid support are presented. The first noncovalent immobilization method, an anionic support to immobilize a positively charged chiral catalytic complex, included the direct cationic exchange of the complex performed in solution and the formation of the complex on a pre-exchanged metal center. The immobilization of PhBox-CuCl 2 and BnBox-CuCl2 complexes result in the loss of chloride couteranion during the exchange process, so that catalytic complex is firmly bound to the anionic support through electrostatic interactions. The immobilization of Mn complex resulted in catalyst that led to moderate enantioselectivity in the epoxidation and a slight reduction from the value obtained in the solution.