Electrooxidative Synthesis of Bis- and Oligoarenes

In this joint project the mechanism and scope of a new electrooxidative biaryl coupling of substituted arenes will be explored and defined. This electrochemical approach has the advantage that no leaving functionalities are required for biaryl cross-coupling. Since no reagent waste is formed in this reagent- and metal free electroorganic process, a highly sustainable synthetic method will be established. The use of electricity and solvent effects to direct the selectivity of the cross-coupling creates a cutting- edge technique in contemporary organic synthesis. This concept based on the decoupling of nucleophilicity and oxidation potential of the substrates can be considered as a new type of umpolung and allows outstanding coupling selectivity. The efficiency of this new methodology will be exploited for the efficient and modular synthesis of mimetics for a-helices based on teraryl and quateraryl architectures. The strategy involves a complementary combination of modern metal-catalyzed steps as well as electrosynthetic transformations which do not require leaving functionalities and provide a direct and sustainable access to such entities.

Linking aromatics to larger units is a very important reaction for the synthesis of important pharmaceuticals and materials. In this project, the groups of Prof. Waldvogel at the University of Mainz and Prof. Breinbauer at the Graz University of Technology were able to show that phenols can be converted under very mild conditions and without waste to 4,4'-biphenols using an efficient electrochemical process. The resulting molecules are useful starting materials for the palladium-catalyzed cross-coupling with aromatic building blocks. With this strategy oligoarenes are accessible, which can be used as inhibitors of protein-protein interactions.