Studien zu enantioselektiven organokatalysierten Domino-Reaktionen (English shop)

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This project aimed to examine the applicability of modern organocatalysts in domino reactions developed in the Tietze group that appeared suitable for this purpose. To this end, commercially available organocatalysts such as L-proline, its thio analogues and cinchona alkaloids were employed, and organocatalysts known from the literature were also synthesised. It was shown that domino Knoevenagel–hetero-Diels–Alder reactions can be carried out efficiently with amino catalysts at room temperature in short reaction times and consistently very good yields, although no asymmetric induction could be observed. Domino Knoevenagel–Sakurai and domino Knoevenagel–Alder–ene reactions proved unsuitable for asymmetric organocatalysis in the systems investigated. First encouraging tests on the use of chiral organocatalysts in the AlMe3-promoted domino amidation–Michael reaction led to the synthesis of an oxygen-free organocatalyst according to Ley. In the course of the subsequent investigations it was found that, although its use increased the yield in some cases, no asymmetric induction could be achieved here either. Experiments with enantiomerically pure products of the domino reaction showed that these racemised under the reaction conditions, which means that the domino amidation–Michael reaction is generally unsuitable for being conducted with asymmetric catalysts. The potential of a newly developed concept for the use of a C2-symmetric promoter was substantiated by calculations using density functional methods; however, initial experiments with such a newly synthesised promoter likewise yielded only racemic products.