Polymergebundene Homogenkatalysatoren : Untersuchungen zum Einfluss des Polymerrückgrates auf die Produktselektivität

Immobilized chiral catalysts, synthesized by means of ring opening metathesis polymerisation (ROMP), have been evaluated with respect to structural and conformational influences. Therefore, a number of different chiral precursors suitable for ROMP have been synthesized. Statistic copolymerisation of these together with achiral monomers furnished a variety of different macromolecular catalysts. The ratio of chiral to achiral repetition units proved to be decisive for good product selectivity in the catalytic reaction. Employing enantiomerically pure norbornene fragments for the ROMP led to the investigation of cooperative effects of the then homochiral polymer backbone and the chiral amino alcohol attached to it. It could be shown that the configuration of the norbornene fragment plays an important role in the formation of immobilized catalysts for enantioselective transformations. It predominates the conformation of the polymer backbone and consequently the microenvironment of the ligand attached to that backbone. In addition, ROMP was utilized for the synthesis of a polymeric 1,4,7-triazacyclononane containing catalyst precursor