Asymmetric Hydrogenations of Unfunctionalized Alkenes Mediated by Ir-N-Heterocyclic Carbene Complexes

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The focus of this research will be to use a semi-rational approach to catalyst design. Heterocyclic derivatives of amino acids would be used to prepare large libraries of ligands by combining smaller libraries of building blocks. Second, hydrogenations of several key alkenes would be examined including novel substrates (cyclopropenes, cyclobutenes, a tetrasubstituted alkene) will be examined to illustrate the generality of the method and to provide products that are not easy to prepare via other methods. Also, a chiron for a common steroidal side-chain containing a useful 1,1-disubstituted alkene will be prepared, but the emphasis of the work would be toward developing reactions that lead to 1,3-di- and 1,3,5-trimethylated chirons. These are important structures in natural product syntheses, and the proposed hydrogenation route is potentially superior to the asymmetric alkylation strategies that are currently in use. With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Dr. Kevin Burgess in the Department of Chemistry at Texas A&M University. Professor Burgess will focus his work on the development of methodology for the asymmetric hydrogenation of unfunctionalized alkenes. Economical, diversity-oriented ligand syntheses will be developed so that libraries of complexes become readily accessible for screening with different substrates. Also, a great range of substrates will be studied, focused on those that lead to genuinely useful chirons. The work has potential for broader impact in the pharmaceutical industry and the project serves as an excellent venue for the training of undergraduates, graduate students and postdoctorals.