Cluster: Integrale Konzepte der Katalyse II(D4)

The project includes the development of unprecedented catalytic routes for the synthesis of fluorinated aromatic and heteroaromatic building blocks, which were not available before. These novel fluorinated entities will subsequently be applied for the catalytic generation of ncAAs.

To achieve the envisaged transformations new catalyst precursors will be developed. The investigations involve the preparation of highly reactive boryl complexes for borylation reactions. The obtained borylated aromatics will then be used in cross coupling reactions to target ncAAs. The nickel and palladium catalysts for the latter are characterized by bulky hemilabile coordinating phosphines. In a second approach fluorinated aldehydes will be synthesized by photocatalytic C-H activation reactions mediated by rhodium carbonyl complexes. Studies on a Strecker-like conversion on using these aldehydes and chiral Lewis-acidic catalysts will lead to fluorinated ncAAs. The essential approach in all these investigations is a comprehensive understanding of mechanistic details of the catalytic cycles and key-steps, which will provide the foundation for the enfolding of new catalytic processes.

Principal Investigators
Braun, Thomas Prof. Dr. (Details) (Inorganic Chemistry)

Participating external organizations

DFG-Exzellenzinitiative: Cluster

Duration of Project
Start date: 11/2012
End date: 10/2017

Research Areas
Anorganische Chemie

L. Zámostná, M. Ahrens, T. Braun, J. Fluorine Chem. 2013, 155, 132-142.
"Catalytic hydrodefluorination of fluoroaromatics with silanes as hydrogen source at a binuclear rhodium complex: Characterization of key intermediates"

M. Teltewskoi, S. I. Kalläne, T. Braun, R. Herrmann, Eur. J. Inorg. Chem. 2013, 33, 5762-5768.
"Synthesis of Rhodium(I) Boryl Complexes: Catalytic N–H Activation of Anilines and Ammonia"

M. Chilleck, T. Braun, B. Braun, S. Mebs, Organometallics 2014, 33, 551-560.
"Neutral and Cationic Zinc Complexes with N- and S-Donor-Functionalized Cyclopentadienyl Ligands"

S. I. Kalläne, T. Braun, B. Braun, S. Mebs, Dalton Trans. 2014, 43, 6786-6801.
"Versatile reactivity of a rhodium(I) boryl complex towards ketones and imines"

G. Meier, V. Steck, B. Braun, A. Eißler, R. Herrmann, M. Ahrens, R. Laubenstein, T. Braun, Eur. J. Inorg. Chem. 2014, 2793-2808.
"Synthesis and Structures of Fluorinated (β-Diketiminato)rhodium Complexes: Si-H Activation of Silanes at a Carbonyl Complex"

S. I. Kalläne, T. Braun, Angew. Chem. 2014, 126, 9465-9469; Angew. Chem. Int. Ed. 2014, 53, 9311-9315.
"Catalytic Borylation of SCF3-Functionalized Arenes by Rhodium(I) Boryl Complexes: Regioselective C-H Activation at the ortho-Position"

R. Herrmann, T. Braun, S. Mebs, Eur. J. Inorg. Chem. 2014, 28, 4826-4835.
"[Ge(H)(2-C6H4PPh2)3] as Ligand precursor at Ruthenium: Formation and Reactivity of [Ru(Cl){Ge(2-C6H4PPh2)3)}]"

T. Ahrens, J. Kohlmann, M. Ahrens, T. Braun, Chem. Rev. 2015, 115, 931-972.
"Functionalization of Fluorinated Molecules by Transition-Metal-Mediated C-F Bond Activation to Access Fluorinated Building Blocks"

S. I. Kalläne, M. Teltewskoi, T. Braun, B. Braun, Organometallics 2015, 34, 1156-1169.
"C-H and C-F Bond Activations at a Rhodium(I) Boryl Complex: Reaction Steps for the Catalytic Borylation of Fluorinated Aromatics"

L. Zámostná, S. Sander, T. Braun, R. Laubenstein, B. Braun, R. Herrmann, P. Kläring, Dalton Trans. 2015, 44, 9450-9469.
"Synthesis and structure of rhodium(I) silyl carbonyl complexes: photochemical C-F and C-H bond activation of fluorinated aromatic compounds"

S. I. Kalläne, T. Braun, M. Teltewskoi, B. Braun, R. Herrmann, R. Laubenstein, Chem. Commun. 2015, 51, 14613-14616.
"Remarkable reactivity of a rhodium(I) boryl complex towards CO2 and CS2: isolation of a carbido complex"

F. Liebau, T. Braun, B. Braun, J. Fluorine Chem. 2015, 180, 192-200.
"Dehydrogenation of cycloalkanes at rhodium complexes bearing fluorinated cyclopentadienyl ligands"

R. Laubenstein, M.-D. Serb, U. Englert, G. Raabe, T. Braun, B. Braun, Chem. Commun. 2016, 52, 1214-1217.
"Is it all in the hinge? A kryptoracemate and three of its alternative racemic polymorphs of an aminonitrile"

C. Berg, R. Laubenstein, T. Braun, B. Braun, Chem. Commun. 2016, 52, 3931-3934.
"Palladium-mediated borylation of pentafluorosulfanyl functionalized compounds: the crucial role of metal fluorido complexes"

B. Calvo, J. Wuttke, T. Braun, E. Kemnitz, ChemCatChem. 2016, 8, 1945-1950.
"Heterogeneous Catalytic Hydroarylation of Olefins at a Nanoscopic Aluminium Chlorofluoride"

T. Ahrens, B. Schmiedecke, T. Braun, R. Herrmann, R. Laubenstein, Eur. J. Inorg. Chem. 2017, 3, 713-722.
"Activation of CS2 and COS at a Rhodium(I) Germyl Complex: Generation of CS and Carbido Complexes"

A. K. Siwek, M. Ahrens, M. Feist, T. Braun, E. Kemnitz, ChemCatChem 2017, 9, 839-845.
"Activation of Chlorinated Methanes at the Surface of Nanoscopic Lewis Acidic Aluminum Fluorides"

G. Meißner, D. Dirican, C. Jäger, T. Braun, E. Kemnitz, Catal. Sci. Technol. 2017, 7, 3348-3354.
"Et3GeH versus Et3SiH: controlling reaction pathways in catalytic C-F bond activations at a nanoscopic aluminium chlorofluoride"

J. Kohlmann, T. Braun, R. Laubenstein, R. Herrmann, Chem. Eur. J. 2017, 23, 12218-12232.
"Suzuki-Miyaura Cross-Coupling Reactions of Highly Fluorinated Arylboronic Esters: Catalytic Studies and Stoichiometric Model Reactions on the Transmetallation Step"

J. Kohlmann, T. Braun, J. Fluorine Chem. 2017, 203, 140-145.
"Synthesis and reactivity of a cationic palladium complex as possible intermediate in a Suzuki-Miyaura cross-coupling reaction"

R. Laubenstein, M. Ahrens, T. Braun, Z. Anorg. Allg. Chem. 2017, 643, 1723-1729.
"Synthesis and Structures of Gallium-β-Diketiminate Complexes: Isolation of a Dinuclear Gallium(II) Complex"

G. Meißner, K. Kretschmar, T. Braun, E. Kemnitz, Angew. Chem. 2017, 129, 16556-16559; Angew. Chem. Int. Ed. 2017, 56, 16338-16341.
"Consecutive Transformations of Tetrafluoropropenes: Hydrogermylation and Catalytic C−F Activation Steps at a Lewis Acidic Aluminum Fluoride"

Last updated on 2020-21-03 at 23:15