Datensatz

Zusammenfassung

The development of Brønsted acid catalyzed asymmetric hydrofunctionalizations of unbiased olefins is described.
In the first part of this thesis, the development of an enantioselective organocatalytic intramolecular hydroalkoxylation of simple olefins is presented. By developing a new class of sterically confined, strong Brønsted acid catalysts, various 1,1-disubstituted olefins were converted to the corresponding 2,2-disubsutituted tetrahydrofurans in excellent yields and enantioselectivities. The method could also be applied to enantiomerically pure substrates, enabling catalyst-controlled diastereoselective cyclizations independent of existing stereogenic centers.
Thorough mechanistic investigations, including both experimental and theoretical analysis, were conducted in order to elucidate the catalytic cycle, suggesting an asynchronous concerted mechanism.
In the second part, the developments of asymmetric organocatalytic hydroarylations of unbiased olefins are described. Various arenes could be used as nucleophiles furnishing products with benzylic all-carbon quaternary stereocenters in good yields and enantioselectivities.