Biomimetic Copper Complexes
Selective oxidations of organic substrates using molecular oxygen under mild conditions are of great interest for organic syntheses in terms of safety, efficacy, and cost-effectiveness. In nature, metalloenzymes use dioxygen as an oxidant under ambient conditions. One example are copper proteins, playing a key role in numerous metabolic processes.[1] They are responsible for binding, activation, reduction and transport of dioxygen. One prominent example is tyrosinase; a copper enzyme that, among other things, catalyses the first step in melanin synthesis, where monophenol is hydroxylated to ortho-diphenol and subsequently oxidised to ortho-quinone. The active centre of the enzyme contains two copper ions, that bind and therefore activate molecular dioxygen for the oxidation of phenol (figure 1).[2]
Figure 1: Oxidation of mono-phenol by tyrosinase (top) and active centre of the enzyme (bottom).[2]
Following the example of copper proteins, biomimetic model complexes are designed to understand and mimic the functioning and reaction mechanisms of natural enzymes. Model complexes provide a precise control over the electronic and geometric properties of the ligands. These ligands stabilise the copper-dioxygen adducts, improve hydroxylation, and lead to the main goal of oxidising C-H bonds.
Currently, we focus on the synthesis and derivatisation of nitrogen containing ligands. By utilising corresponding copper(I) complexes and molecular oxygen, we investigate the efficacy of various copper-oxygen species for the oxidation of aliphatic compounds. The primary goal is to identify which species are most suitable for oxidative reactions, thereby advancing the understanding and application of these processes in organic synthesis.
[1] a) M. Pascaly, I. Jolk, B. Krebs, Chem. Unserer Zeit 1999, 33, 334; b) R. Jacobson, Z. Tyeklar, A. Farooq, K. D. Karlin, S. Liu, J. Zubieta, J. Am. Chem. Soc. 1988, 3690.
[2] Jonathan Becker, Synthetic and Kinetic Investigations on Selective Oxidation of Aromatic and Aliphatic Hydrocarbons with Copper Complexes, Universitätsbibliothek, Gießen, 2015.
| Project-Director: | Prof. Dr. Richard Göttlich |
|---|---|
| Co-Workers: |
M. Sc. Luisa Träger |