Topic: Boron-Centered Nucleophilicity in Clusters
Speaker: Professor Alex Spokoyny - University of California at Los Angeles
Host: Professor Aaron Odom
Date: Monday, March 18, 2019
Time: 11:20 AM
Location: 136 CEM
200 years of research with carbon-rich molecules have shaped the development of modern chemistry. Research pertaining to the chemistry of boron-rich species has historically trailed behind its more distinguished neighbor (carbon) in the periodic table. Most importantly, a potentially rich and, in many cases, unmatched field of using boron-rich clusters in materials science remains fundamentally underdeveloped. Our work is devoted towards examining several basic concepts related to the functionalization of polyhedral boron-rich clusters and their use as unique building blocks for materials with applications ranging from catalysis to modulating protein-biomolecule interactions.
My presentation will focus on the aspects of fundamental chemistry associated with the functionalization of boron clusters. Specifically, we have been interested in the generation and reactivity studies of B-centered nucleophiles associated with these species. During the first half of the talk, I will describe how the nucleophilic character of the boron vertices in some of these clusters can be harnessed by using late transition metal chemistry. These observations have guided our development of several synthetic methodologies enabling derivatization of these species in a catalytic fashion via pathways that are reminiscent of classical metal-catalyzed cross-coupling chemistry with organic substrates. Furthermore, we have recently successfully applied this strategy for bioconjugation transformations with unprotected peptides. In the second half of the presentation, I will demonstrate how some boron clusters can act as competent nucleophiles without the aid of transition metals. I will highlight some unique features of the nucleophilic character of the small boron clusters that can be applied to carbon-based electrophiles as well as main-group electrophiles (e.g., R2PCl, RSeCl) to generate the corresponding borylated species featuring B-C, B-Se and B-P bonding interactions. We envision subsequent transfer and/or addition chemistry using nucleophilic boron cluster reagents to be a highly valuable addition to the arsenal of synthetic chemists.