The development of selective catalysts for novel C-N- and C-C-bond forming reactions - a contribution to a more sustainable chemistry

• Applicant: Professor Dr. Rhett Kempe
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2012 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 221509923

Aims of the submitted proposal are the development of novel catalytic reactions and the development of catalyst classes able to mediate these reactions efficiently. Dehydrogenation and condensation steps are combined in the reactions to synthesize N aromatic compounds from various alcohol components. Alcohols are accessible via pyrolysis from lignocellulose, a natural resource available in large amounts and barely used. Thus, the catalytic concepts developed in the proposal can be understood as a contribution to a more sustainable chemistry.The state of the art in the field of ADC (acceptorless dehydrogenative condensations) for the catalytic synthesis of N aromatic compounds is internationally strongly influenced by our contributions. In the last (first) period of funding, we published five manuscripts, partially in high impact journals like Nature Chemistry and Angewandte Chemie. The investigation of the following interlinked sub-projects is proposed for the second period of funding.Development of novel catalytic reactionsFirstly, the extension of the ADC concept towards the catalytic synthesis of N-rich aromatics is proposed. In this sub-project, we plan, on the one hand side, to investigate reactions of amino alcohols with various C-N multiply bonded species. Furthermore, we plan the development of multi component reactions, in which up to three alcohol components, ammonia and nitriles are linked to highly functionalized pyrimidines. Conceptually new is the third aim. ADC is combined with hydrogenation and dehydrogenation steps to allow a broadly applicable and sustainable access to polycyclic N aromatic compounds.Catalyst designThree aims are in focus with regard to the catalyst design part of the proposal. Firstly, we plan the development of novel Ir and Ru complex-catalysts stabilized by hydrolysis stable ligands. Water is eliminated in ADC reactions and more stable catalysts are imaginable if the used ligands tolerate it. Preliminary work shows a superiority of such catalyst in comparison to the Ir complex-catalysts used in the pyrrole synthesis so far. Secondly, we are interested in developing Co and Fe catalysts for ADC. The use of inexpensive base metals as an alternative for the so far used Ir and Ru catalysts seems possible as preliminary work with Co indicates. Thirdly, the development of efficient reusable catalysts for the selective hydrogenation of arenes and the dehydrogenation of cycloalkanes is proposed. They are needed for the synthesis of polycyclic N aromatic compounds via a hydrogenation, ADC and dehydrogenation sequence.

• DFG Programme: Research Grants