Green Chemistry using Early Transition Metal Catalysts for the Synthesis of Small Molecules and Materials

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Nitrogen containing chemicals, amines, are key components of biological assemblies, like proteins and DNA, as well as synthetic products such as pharmaceuticals, agrochemicals and responsive materials. Amine containing materials are high-value products that have diverse applications ranging from CO2 capture materials to anti-microbial coatings. Due to the prevalence of amines in useful commercial products, chemists have developed many ways to selectively install nitrogen into compounds, many of which generate significant waste. My program aims to develop sustainable technologies for chemical industries that make amine containing molecules and materials. Over the years the Schafer group has advanced green chemistry by developing catalysts for the selective, atom-economic synthesis of amines. Also, this research program features the use of 3d early transition metals, titanium and vanadium, which are abundant, of low cost and low toxicity.  Our understanding of these catalysts have inspired investigations with alcohols, rather than amines. Alcohols can be renewably obtained from biomass sources and are key building blocks for transitioning chemical manufacturing into the circular economy. Our research program has pioneered the development of a class of catalysts that feature N,O-chelating ligands as key components to modify catalytic activity. The N,O-chelating framework is easily modified, making it simple to rapidly identify improved or even new transformations. Trainees at the undergraduate, graduate and postdoctoral levels complete detailed structural, kinetic and computational mechanistic experiments to understand how these transformations occur. These insights guide enhanced catalyst development efforts and have resulted in world-leading hydrofunctionalization reactions of alkynes with amines and broadly useful catalysts for the direct, catalytic amination of alkenes by hydroaminoalkylation. Over the past six years we have shown that ureate N,O-chelated complexes of tantalum promote this reaction with a broad range of amines and alkenes and we have learned how to control both the regio- and diastereoselectivity of these transformations. Here we propose to apply titanium variants of these catalysts in alternative bond-making strategies for preparing amino acids and a variety of N-heterocycles that are prevalent in natural products and drug molecules. We also propose to prepare new amine functionalized polymers that will be investigated, in collaboration with academic and industrial partners, for use as anti-corrosion coatings, anti-microbial additives, and CO2 capture materials. We also seek to develop catalysts that can generate the alkene starting materials that we need for hydrofunctionalization reactions, by using alcohol coupling reactions in a modified McMurry coupling. Thus, this proposal aims to push toward using biomass derived, renewable resources for the synthesis of high-value small molecule amines and materials.