Jump to contentJump to search

Our research

Current Research

The subject of our research is the development of new stereoselective synthesis methods with chiral transition metal complexes, photocatalysts as well as electrosynthetic methods for the preparation of highly functionalized building blocks. Another field of work includes the preparation of new materials as well as addressing topics in medicinal chemistry related to neurodegenerative diseases such as Alzheimer's disease.

1) Heterofunctionalization of Unsaturated Hydrocarbons

Cationic gold complexes can activate alkenes or alkynes towards the attack of a nucleophile and are therefore suitable catalysts for these functionalizations. 1,4-Diynes with an internal nucleophile undergo desymmetrization to form a chiral, heterocyclic compound. The specific substitution pattern determines the regioselectivity:

In the presence of an optically active counter-anion pyrrolidines with a quaternary stereocenter are obtained enantioselectively under suitable conditions and can be further functionalized regioselectively. An application of this method is the enantioselective total synthesis of indole alkaloid natural products such as mesembrine.

2) Stereoselective Halogenations and Fluoroalkylations

The preparation of chiral halogenated compounds is of great synthetic interest, but it is not as well- established as the corresponding O- and N-functionalizations. In particular, we are interested in halogenations of simple alkenes and Michael acceptors. Thus, we were able to develop a stereoselective fluoroalkylation of crotonic acid derivatives, which provides a new access to highly functionalized synthetic building blocks such as fluorinated amino acids or nucleosides.

With the aid of simple phosphines or phosphites, perfluoroiodoalkanes add to alkenes and alkynes under photocatalytic conditions. Blue LED light is sufficient for this purpose. The activation of the iodoalkane probably occurs via a halogen-bonded electron-donor-acceptor complex. For this transformation, we have developed a photoreactor whose components can be easily fabricated using a 3D printer.


3) Photophysical properties of selectively fluorinated flavin derivatives

Flavins play an important dual role in biological systems. As redox mediators they serve as a pivotal cofactor in many central biochemical transformations. In addition, flavins are employed by nature for both bioluminescent systems and blue light-absorbing photoreceptors. A modification in the substitution pattern of the flavin core has a tremendous impact on their photophysical properties. In particular fluorine is interesting in this respect due to the high electronegativity and small size. For the synthesis of regioselectively fluorinated flavins, novel synthetic methodology for late-stage fluorination are developed involving transition metal catalysis as well as photocatalysis and electrosynthesis.

4) Derivatives of Natural Products for Potential Treatment of Neurodegenerative Diseases

Green tea has long been established in traditional Chinese medicine. A few years ago, an active ingredient isolated from it – epi-gallocatechin gallate (EGCG) – proved to be a promising candidate for the treatment of neurodegenerative diseases such as Alzheimer's disease. As a result of the demographic development in industrialized countries, the importance of these diseases is steadily increasing. In order to better understand the specific mechanism of action and to make clinical therapy possible, we prepare new, synthetic EGCG derivatives and investigate their efficacy as well as their mechanism of action in cooperation with medically and pharmacologically oriented research groups.

Responsible for the content: