Preparation and Catalytic Properties of Immobilized Chiral Dirhodium(II) Carboxamidates

Abstract

Chiral dirhodium(II) tetrakis[methyl 2-oxypyrrolidine-5(S)-carboxylate] has been immobilized on polystyrene−poly(ethylene glycol) and Merrifield resins. Intra- and intermolecular cyclopropanation reactions with these catalysts demonstrate their high selectivity, comparable to or better than their homogeneous counterpart, and recovery and reuse for up to nine sequential applications have been achieved without loss of selectivity. Catalyst stability is related to the percentage of available sites to which the ligand is affixed, but the percentage of ligand sites on the polymer that are bound to dirhodium(II) does not appear to influence stability or selectivity.