Synthesis and Reactions of Carbene Boranes

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Project SummaryIn this project funded by the Chemical Synthesis Program of the Chemistry Division, Professor Dennis P. Curran of the Department of Chemistry at University of Pittsburgh will explore objectives in small molecule synthesis, polymer synthesis, and main group chemistry. The concepts and methods of this work deepen and broaden the disciplines of small molecule synthesis and help in the quest to provide the molecules, materials, and technologies that other disciplines rely on to progress. This is being accomplished with a broad focus on sustainable chemistry by using the common second row element boron (readily available, not toxic, and recyclable) to replace the rare, expensive and/or toxic elements typically employed to drive new reaction discovery. The program is characterized by a strong coupling between advancing the frontiers of science and teaching and training a diverse group of undergraduate students and graduate students. These students move into the workplace to become the human capital that drives progress in many areas that are vital to the health of our citizenry and the economy of our nation. The project also regularly uses cutting edge technology like videoconferences to manage intercontinental collaborations. These collaborations expand the direct teaching/training impact of the proposal beyond Pittsburgh to France, Japan and Scotland.The main focus of this proposal is the development of new boron based methods for synthesis. Much of the work centers on the newly discovered double hydroboration reaction of electron poor alkynes by N-heterocyclic carbene boranes (NHC-boranes). The reactions afford strained boriranes (boracyclopropanes) and an opportunity to discover new, sustainable pathways for the construction of functionalized organic molecules. The scope and mechanism of this unusual new reaction is being studied along with the chemistry needed to replace the NHC-borane group in the product with carbon-carbon and carbon-oxygen bonds. In addition, work toward the development of NIH-difluoroboranes is being pursued in connection with the opportunities for new bond formation that these intermediates afford.