**Synthesis of a Bcl9 Alpha-Helix Mimetic for Inhibition of PPIs by a Combination of Electrooxidative Phenol Coupling and Pd-Catalyzed Cross Coupling** †

**Martin Vareka <sup>1</sup> , Benedikt Dahms <sup>2</sup> , Mario Lang <sup>1</sup> , Minh Hao Hoang 1,3, Melanie Trobe <sup>1</sup> , Hansjörg Weber <sup>1</sup> , Maximilian M. Hielscher <sup>2</sup> , Siegfried R. Waldvogel 2,\* and Rolf Breinbauer 1,\***


Received: 12 February 2020; Accepted: 16 March 2020; Published: 19 March 2020

**Abstract:** Teraryl-based alpha-helix mimetics have resulted in efficient inhibitors of protein-protein interactions (PPIs). Extending the concept to even longer oligoarene systems would allow for the mimicking of even larger interaction sites. We present a highly efficient synthetic modular access to quateraryl alpha-helix mimetics, in which, at first, two phenols undergo electrooxidative dehydrogenative cross-coupling. The resulting 4,40 -biphenol is then activated by conversion to nonaflates, which serve as leaving groups for iterative Pd-catalyzed Suzuki-cross-coupling reactions with suitably substituted pyridine boronic acids. This work, for the first time, demonstrates the synthetic efficiency of using both electroorganic as well as transition-metal catalyzed cross-coupling in the assembly of oligoarene structures.

**Keywords:** alpha-helix; anode; CH-activation; cross-coupling; electrosynthesis; oligoarene; peptidomimetics; phenol; protein-protein interactions; triflate
