Asymmetric aziridination of cyclic enones via counterion enhanced organocatalysis

Abstract

The focus of the present thesis is the asymmetric aziridination of cyclic enones via counterion enhanced organocatalysis. In this approach, the catalyst system consists of a chiral diamine, which can be obtained from an amino-acid precursor, and an achiral phosphoric acid, which combine to form the catalyst salt. In order to determine the best performing catalyst system and the optimal reaction conditions, several amines, phosphoric acids, bases and solvents were screened. After optimizing the parameters, the asymmetric aziridination was successfully applied to a range of 3- and 4-substituted cyclohexenone substrates, in a final step. With this new catalyst system, excellent enantioselectivities as well as good yields could be achieved for several substrates and consequently, the versatility of the concept of counterion enhanced organocatalysis could be demonstrated.