Design of chiral Cp*-like ligands and application in asymmetric C–H activation reactions

• Applicant: Dr. Alissa Cordula Götzinger
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2017 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 389961129

During my postdoc project, I am planning to work on the development of novel chiral Cp*-like ligands and their application in asymmetric C–H activation reactions. Cyclopentadienyl (Cp) and pentamethylcyclopentadienyl (Cp*)-type ligands are privileged ligand classes for a variety of transition metals. Their corresponding metal complexes are the catalysts of choice for a broad range of C–H activations. Asymmetric variants, however, were extremely scarce until a few years back when Cramer and coworkers developed two different classes of chiral monodentate disubstituted Cpx ligands. These induce chirality based solely upon steric shielding of the metal centre. The respective rhodium and iridium complexes were succesfully employed in different asymmetric transformations.Cp and Cpx-type complexes are, however, not the optimal catalysts for many transformations as the best reactivity in achiral C–H activation reactions is often achieved with pentamethylcyclopentadienyl (Cp*) complexes. This leads to big differences in reactivity between the established chiral disubstituted Cpx catalysts and achiral pentasubstituted systems.We are planning to address this problem by replacing the three hydrogen atoms on the established Cpx ligands by methyl groups, resulting in the respective pentasubstituted, chiral Cp*-like species. Once we have this scaffold in hand, late modification of the substituents gives access to a ligand library with different steric and electronic properties. These ligands will be complexed with different transition metals, starting with the respective cobalt(III) and iridium(III) complexes. To evaluate the reactivity of these novel catalysts, chiral versions of Cp*-catalysed transformations will be developed in which the established chiral Cpx systems show little or no reactivity.

• DFG Programme: Research Fellowships
• International Connection: Switzerland
• Host: Professor Dr. Nicolai Cramer