Asymmetrische Katalysen, 13 [1]. Chelat-Liganden und ihre Rhodium-Komplexe mit seitlichen Asymmetriezentren und ihre Anwendung in der enantioselektiven Katalyse / Asymmetric Catalyses. 13 [1]. Chelate Ligands and their Rhodium Complexes with Lateral Asymmetrie Centers and their Use in Enantioselective Catalysis

Abstract

Abstract The chelate ligands 1-3 with lateral asymmetric centers at the nitrogen atoms were prepared and characterized. In the Rh complexes 4 and 5 the asymmetric centers directly interact with those coordination positions where during enantioselective catalysis pro-chiral substrates are converted into optically active products. The compounds 4 and 5, as well as the in situ catalysts [Rh(COD)Cl]2/2 were used in the asymmetric hydrogenation of α-N[acetamino]cinnamic acid and in the asymmetric hydrosilylation of acetophenone with diphenylsilane. The low optical inductions obtained result from the catalyst loosing its chiral information during catalysis due to racemization or fragmentation.