Sensitization-Initiated Electron Transfer for Photoredox Catalysis

Angewandte Chemie - International Edition

5 years ago

Sensitization-Initiated Electron Transfer for Photoredox Catalysis

Indrajit Ghosh, Burkhard König, Rizwan S. Shaikh

Photosynthetic organisms exploit antenna chromophores to absorb light and transfer excitation energy to the reaction center where redox reactions occur. In contrast, in visible-light chemical photoredox catalysis, a single species (i.e., the photoredox catalyst) absorbs light and performs the redox chemistry. Mimicking the energy flow of the biological model, we report a two-center photoredox catalytic approach in which the tasks of light energy collection and electron transfer (i.e., redox reactions) are assigned to two different molecules. Ru(bpy)3Cl2 absorbs the visible light and transfers the energy to polycyclic aromatic hydrocarbons that enable the redox reactions. This operationally simple sensitization-initiated electron transfer enables the use of arenes that do not absorb visible light, such as anthracene or pyrene, for photoredox applications. We demonstrate the merits of this approach by the reductive activation of chemical bonds with high reduction potentials for carbon–carbon and carbon–heteroatom bond formations. Inspired by nature: In the presented two-center photoredox catalytic approach, Ru(bpy)3Cl2 absorbs visible light and transfers the energy to polycyclic aromatic hydrocarbons, which in turn enable an efficient redox process. This method was used for the activation of (hetero)aryl halides for the formation of carbon–carbon and carbon–heteroatom bonds.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201703004