Research
The “Clip-and-Cleave” Concept
Aromatic and aliphatic ketones and aldehydes can be hydroxylated regioselectively using copper(I) complexes and O2 as oxidant. Initially, the substrates are “clipped” to a directing group by imine condensation. Subsequently, the resulting chelate ligand coordinates to copper(I), which then facilitates the hydroxylation by activation of O2. Finally, the imine is “cleaved” by aqueous workup to release the product. We are interested in further developments of this concept and understanding the underlying mechanisms behind this type of reaction.
A. Petrillo et al., Eur. J. Inorg. Chem. 2022, e202100970; P. Specht et al., Eur. J. Inorg. Chem. 2021, 1961; J. Becker et al., Chem. Eur. J. 2018, 24, 15543; J. Becker et al., Chem. Eur. J. 2015, 21, 11735.
Copper Enzyme Model Complexes
Copper-containing enzymes are ideal biomimetic models for “green” oxidation catalysts since their reactions use O2 as oxidant work under ambient conditions in water and produce only H2O and H2O2 as by-products. Our goal is the synthesis of ligands that mimic the copper enzyme active sites, to gain further understanding of the processes and intermediates revolving dioxygen activation in such enzymes.
M. Bhadra et al., J. Am. Chem. Soc. 2021, 143, 3707; M. Lerch et al., Eur. J. Inorg. Chem. 2020, 3143; S. Schaub et al., Angew. Chem. Int. Ed. 2018, 57, 5355; C. Würtele et al., Angew. Chem. Int. Ed. 2006, 45, 3867.
3d Metal complex mediated Oxidations and Oxygenations using “Clean” Oxidants
Oxidation and oxygenation reactions are key technologies for the chemical industry value chain according to the German Catalysis Society. We are interested in developing such reactions using “green” oxidants such as O2, O3, and H2O2 catalyzed by 3d metal complexes with various ligands. Exemplary reactions of this type are the oxidation of toluene to benzaldehyde or the oxidation of cyclohexanone to adipic acid.
M. Lerch et al., Eur. J. Inorg. Chem. 2021, 4122; T. Brückmann et al., Z. Anor. Allg. Chem. 2021, 647, 560; C. Gawlig et al., Eur. J. Inorg. Chem. 2020, 248; C. Würtele et al., J. Am. Chem. Soc. 2009, 131, 7544.
Copper Mediated Oxygenations in Water
The next step in the development of “green” oxygenations (besides using green oxidants) would be the use of water as an economic and environmentally friendly solvent. Therefore, we are working on the development of water-soluble copper complexes, which can be used for catalytic oxygenations in water.