Achieving Challenging Synthesis Based on Triazole-Gold Catalysis

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With support from the Chemical Synthesis (SYN) Program in the Division of Chemistry, Xiaodong Shi of the University of South Florida will develop new ways to make azaborines and to link alkynes in large ring structures using gold catalysts with a unique structural characteristic called a triazole. Azaborines are benzene-like molecules where two adjacent carbon atoms have been replaced a nitrogen and a boron atom. This structural change gives these molecules important biological properties but makes them challenging to prepare. Large ring alkynes are also difficult to construct but have valuable bioconjugate and biomimetic applications. The gold catalysts being developed by Dr. Shi and his team are being studied to facilitate new ways to easily access a larger variety of these important but challenging compounds. The triazole portion of the gold catalyst will be used to tune this reactivity. These studies will provide undergraduate and graduate students important training in state-of-art chemical synthesis and supporting the preparation of next generation scientist in STEM research. In addition, Dr. Shi is organizing an annual student-oriented research meeting at the University of South Florida for students in the Tampa area to bolster STEM education and further enhance the educational mission of the state of Florida.Gold catalysts have well-established synthetic utility in a variety of cycloisomerization processes, but new ligand scaffolds have the potential to broaden these applications in new directions. Xiaodong Shi and his research group at U. South Florida have determined that triazole ligands impart key properties on gold catalysts that help facilitate novel reactions. In the current project, triazole gold catalysts are being optimized for the hydroboration of alkynyl amino boranes for the synthesis of azaborines and will be investigated for the synthesis of macrocyclic alkynes. Mechanistic studies will also be pursued to understand the role of the triazole motif in supporting these transformations. Complementary synthetic studies are also ongoing to convert the initial catalytic products to value-added synthetic targets. These activities are supporting the training of a diverse group of graduate and undergraduate students and providing needed synthetic alternatives to support practical, large scale synthesis of these interesting target compounds for their further exploration in medicinal chemistry research and in materials science.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.