CAS: Understanding and Controlling the Selectivity of Catalytic Metal-Free C-H Functionalizations

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With funding from the Chemical Catalysis Program of the Chemistry Division, Forrest Michael of the University of Washington is studying how to use more abundant and economical elements as replacements for expensive transition metal catalysts to introduce new functionality in complex organic molecules. As the nation aspires toward a greener, more sustainable future, it is critical that we find new catalysts for synthetic transformations of value that are less expensive and more sustainable. One powerful and efficient way to build new molecules is by selective activation of one of the many carbon-hydrogen bonds in these structures and substitution of that hydrogen with a new chemical group. Though many metal-based catalysts can be used for this purpose, this proposal addresses two major challenges. First, new catalysts based on selenium are being developed as potentially more economical alternatives to existing metal-based methods. Second, because complex organic molecules possess many different types of carbon-hydrogen bonds, the fundamental factors that control the selective replacement of individual hydrogen atoms will be studied and this knowledge will be used to design new ways to make molecules. The broader impacts of this work include more sustainable access to new molecules with novel biological, pharmaceutical, and materials properties. Additionally, Prof. Michael trains scientifically-talented high school students in the US and around the world about cutting-edge research in chemistry and mentors them in research projects in his laboratory, through his work with the Center for Excellence in Education and the Research Science Institute. With funding from the Chemical Catalysis Program of the Chemistry Division, Forrest Michael of the University of Washington is studying what steric, electronic, and structural factors control the high regio- and stereoselectivity of C-H activation catalyzed by novel complexes of selenium developed in his laboratory. Systematic exploration of these factors will likely enable the more widespread use of these catalysts in synthesis by allowing substrates and catalysts that give high selectivity to be predicted and designed ahead of time. Identification of functional groups that strongly direct C-H activation, but which also can be easily transformed into a wide variety of new substituents will likely enable new synthetic strategies for installation of nitrogen groups in complex compounds. Furthermore, the more complete mechanistic understanding obtained from these studies will expand the scope of nitrogen groups that can be introduced using these reactions and lead to new modes of reactivity. The fundamental reaction mechanisms and key intermediates in these transformations will be studied by testing the effects of ligands and additives and by examining intermediates by multi-nuclear (1H, 31P, 77Se) NMR spectroscopy. Dr. Michael is engaged in outreach activities that mentor highly gifted and talented high school scientists through his work with the Center for Excellence in Education and the Research Science Institute.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.