UC Merced

In Chapter 1, tetrahydroxydiboron (B2(OH)¬4)) is shown to effect 2 novel reductions involving palladium. First, we demonstrate a novel synthesis of Pd(PtBu3)2¬ using B2(OH)4 as a reducing agent. Next, I discuss the attempted development of the diboron(4) reagent mediated homogeneous system for the hydrogenation of olefins catalyzed by Pd(PtBu3)2¬, which was unsuccessful. Subsequently, I found and developed a Pd/C catalyzed deoxygenation of aromatic ketones in which B¬2(OH)4 is the sole reductant and hydrogen atom donor. I demonstrated the hydrogen atoms originating on the hydroxyl moieties of B¬2(OH)4 were incorporated into the final deoxygenated product, which had never been demonstrated previously. A small scope of deuterated products is presented using the deuterated ¬B2(OD)4. A key intermediate postulated to be a borate ester was identified and a putative mechanism is proposed, including a key hydrogenolysis of a borate ester. In Chapter 2, I disclose attempts to synthesize thermally responsive emissive compounds based on the TM-DBCOD scaffold. The unique ability of the DBCOD scaffold to exist stably in both the Boat and Chair conformers allows for the potential to design thermally responsive materials. I attempted to exploit this conformational change to reversibly form a species capable of excimer formation based on the spatial separation of the pendant excimer formers, both anthracene and pyrene. Three novel compounds with pendant anthracene or pyrene were synthesized and examined for their photophysical properties. These compounds were designated 1-PyreneAmide, 1-AnthraAmide, and 2-AnthraAmide. 1-PyreneAmide exhibited exclusively excimer emission, indicating spatial separation of ~10Å could not be achieved in this system, regardless of temperature. 2-AnthraAmide exhibited an interesting dependence on solvent polarity indicating an end-to-end overlap excimer may be forming, as a function of solvent polarity. Additionally, 2-AnthraAmide was shown to isomerize into the intramolecular [4+4] photo isomer. Thermal reversion of the proposed photo isomer was observed. Initial results were collected on the 1-AnthraAmide showing probable excimer formation, but further experiments are needed to characterize its behavior. In Chapter 3, I discuss two side projects arising from observations made in the chapter 1 work. First, I discuss the development of a hydride mediated palladium catalyzed hydrogenation of alkenes. A combination of potassium tertbutoxide and pinacol borane effectively mediated hydrogenation of C=C bonds under palladium catalysis. I demonstrated the addition of a stoichiometric oxidant allowed for closure of the catalytic cycle. Next, I discuss the isolation and identification of a benzo oxetane product discovered during the diboron(4) mediated deoxygenation of aromatic ketones work.