Structurally- and Proton-Responsive Ligands for Sustainable Catalysis

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We explore new paradigms in metal ligand reactivity, which allows us to apply and exploit this behaviour in catalysts for the construction of synthetically valuable functionalities. Target transformations include C-C, C-N and C-O bond formations that have the potential to be used in the construction of value-added products such as fragrances, agrochemicals and pharmaceuticals. The specific types of bond constructions will be distinct from existing methods due to the unique metal-ligand reactivity of the catalyst structures. Our research targets three distinct modes of metal-ligand reactivity: 1. Structurally-Responsive Ligands to Promote Bond Formation and Substitution Reactions. We have developed a structurally-responsive ligand and we aim to establish that the ligand dynamics promote organometallic reactions and to elucidate how to control these actions. The exemplar reactions will be Csp3-Csp3 coupling and substitution, which are essential steps in many catalytic reactions and thus have the potential for broad impact to catalysis. 2. Bronsted-Basic Ligands to Promote C-H Activation with Ni(II) for Aerobic Oxidation Catalysis. C-C coupling catalysis has been revolutionized by redox neutral Csp2-H activation by Pd(II) in concert with an intramolecular Bronsted base. We aim to explore Csp3-H activation with Ni(II) and hydroxide as the base. A successful reaction would give only water as an innocuous by-product and the reaction would be compatible with Ni(II) promoted allylic oxidation with O2. Together these reactions would give the unprecedented, selective, one-step, additive-free aerobic oxidation of C-H bonds by nickel. 3. Proton-Transfer Ligands to Promote Additive-Free Intermolecular Hydroamination. Many catalytic reactions include proton-transfer (PT) steps en route to, for example, C-C or C-E bond formation. Instead of an intermolecular base to mediate PT, an internal base on the ligand eliminates the need for additives and can accelerate reaction rates. We aim to apply our experience with PT ligands to develop Ru and Fe catalysts for selective C-N bond formation to give synthetically versatile imine and enamine products.