Asymmetric heterogeneous carbene transfer catalyzed by optically active ruthenium spirobifluorenylporphyrin polymers

Abstract

Anodic oxidation of chiral ruthenium complexes of spirobifluorenylporphyrins leads to the coating of the working electrode by insoluble optically active films whose electrochemical behaviour and physicochemical properties are described. After removal from the electrode, the ruthenium-complexed polymers were evaluated as enantioselective catalysts for the cyclopropanation of olefins by ethyl diazoacetate. The results show the reactions proceeded very efficiently at room temperature with excellent yields (80–90%) and moderate enantioselectivities (up to 53% at −40 °C). The chiral electrosynthesized polymer catalysts can be recycled by simple filtration and reused even up to the seventh cycle with only a slight decrease of activity and enantioselectivity.