Periodic Reporting for period 3 - MetalloRadiCat (Metalloradical Catalysis - From Fundamental Studies to Applications)
Reporting period: 2023-05-01 to 2024-10-31
The project MetalloRadiCat is focused on the combined experimental and computational fundamental study of some of the most challenging aspects in homogeneous metalloradical catalysis.
The group investigated based on previous results (Science 2019, 363, 391) the process of metalloradicals in chain walking at which we developed already a new air-stable Pd-I-dimer, which triggers E-selective olefin migration to enamide and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. (Angew. Chem. Int. Ed. 2020, 59 21930) In a second project we achieved a remote functionalization strategy, which allows the Z-selective synthesis of silyl enol ethers of (hetero)aromatic and aliphatic ketones vie Ni-catalyzed chain walking from a distant olefin site. (Journal of the American Soc. 2021, 143, 8375) Mechanistic studies indicate that a Ni(I) dimer is formed under the reaction conditions which is transformed intermediately to a Ni(II) species as an active chain-walking/functionalization catalyst.
Following our aim to use metalloradicals for the remote functionalization and the assembly of polymers and rings we had been successful to accomplish a method to synthesize novel stuctures like cyclic N-CF3 amides like 4-monosubstituted imidazolidinones. The strategy relies on straightforward cyclization of readily accessible acyclic ureas, enabled by Ag-catalysis or light-assisted proton coupled electron transfer (Chem. Eur. J. 2022, 28, e202201435).
On our way to metallo-catalyzed polymerization we highlighted the use of dinuclear Pd(I)-complexes as both pre-catalysts for the formation of highly active Pd(0) and Pd(II)−H species as well as direct dinuclear catalysts including the investigation of the mechanistic intricacies (Angew. Chem. Int. Ed. 2021, 60, 3355).
Furthermore, we used stable and nontoxic aryl germanes – even under harsh fluorination conditions – to achieve a superior reactivity and functional-group tolerance in electrophilic iodinations and brominations outcompeting silanes and boronic esters under rapid and additive-free conditions. (Angew. Chem. Int. Ed. 2020, 59, 18717) In addition we achieved an optimization of modular and selective arylation of aryl germanes by light-activated gold catalysis. (Angew. Chem. Int. Ed. 2020, 59, 15543)
Following our aim to use metalloradicals for the remote functionalization and the assembly of polymers and rings we had been successful to accomplish a method to synthesize novel stuctures like cyclic N-CF3 amides like 4-monosubstituted imidazolidinones. The strategy relies on straightforward cyclization of readily accessible acyclic ureas, enabled by Ag-catalysis or light-assisted proton coupled electron transfer (Chem. Eur. J. 2022, 28, e202201435).
On our way to metallo-catalyzed polymerization we highlighted the use of dinuclear Pd(I)-complexes as both pre-catalysts for the formation of highly active Pd(0) and Pd(II)−H species as well as direct dinuclear catalysts including the investigation of the mechanistic intricacies (Angew. Chem. Int. Ed. 2021, 60, 3355).
Furthermore, we used stable and nontoxic aryl germanes – even under harsh fluorination conditions – to achieve a superior reactivity and functional-group tolerance in electrophilic iodinations and brominations outcompeting silanes and boronic esters under rapid and additive-free conditions. (Angew. Chem. Int. Ed. 2020, 59, 18717) In addition we achieved an optimization of modular and selective arylation of aryl germanes by light-activated gold catalysis. (Angew. Chem. Int. Ed. 2020, 59, 15543)
Please see above section under “Work performed” for a concise summary. These studies and findings were all beyond state of the art. The co-workers were trained in synthetic organic chemistry, homogeneous metal catalysis as well as state-of-the-art computational and mechanistic chemistry.