Synthesis and Application of Salen Complexes Supported on Poly(norbornene)s and Gold-Nanoparticles

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Asymmetric catalysis is the most powerful method for the synthesis of chiral compounds. While asymmetric catalytic transformations have become more important in the last years, their use in practical applications in industry is limited. The primary restrictions are difficulties in separating and reusing the transition metal catalysts. This is especially true for an important class of asymmetric transformations, the epoxidation of unfunctionalized olefins by chiral metal-salen complexes based on manganese. The aim of the one-year stay in Professor Marcus Weck's group at the Georgia Institute of Technology (Atlanta, USA) is to develop (i) highly active and selektive and (ii) fully reusable supported salen catalysts. To accomplish goal (i) it is important to ensure a good accessibility to the metal centers. This will be achieved by synthesizing monofunctionalized salen-cores tethered to soluble supports such as poly(norbornene)s or gold nanoparticles. Both supports allow for the synthesis of welldefined, immobilized complexes with controllable metal loadings. To achieve goal (ii) degradation of the catalyst during the epoxidation reactions must be minimized. This will be realized by synthesizing catalysts with site-isolated metal centers and stable C-C bond linkages between the linker and the salen core.