PhD defenses.

Metal Hydride Hydrogen Atom Transfer (MHAT) Initiated Annulations in Terpenoid Total Synthesis

Abstract: Terpenoid natural products host a range of potentially valuable biological activities. However, congeners with high degrees of oxidation and steric encumbrance are challenging to prepare by canonical chemical transformations. This problem inspired us to develop a novel annulation capitalizing on metal hydride hydrogen atom transfer (MHAT) chemistry. We leveraged this new annulation in a concise synthesis of a labdane diterpenoid, forskolin and a quassinoid natural product, quassin.

Understanding Proton-Transfer Dynamics of Reversible Excited-State Photoacids Using Driving-Force-Dependent Kinetic Theories

Abstract: In recent years, reversible excited-state photoacids have been exploited for high spatiotemporal sensing of local pH during electrochemical reactions, to study proton-coupled reaction mechanisms, to trigger processes in biological organisms relevant to energy transduction, and in the design of artificial light-driven proton pumps. Successful application of these photoacids in various systems requires non-trivial experimental quantification of accurate excited-state Brønsted-Lowry acidities (thermodynamics) and excited-state proton-transfer rate constants (kinetics

Total Synthesis of Pleuromutilin

Abstract:

The presentation will detail the development of a synthetic route to pleuromutilin, a structurally complex antibacterial diterpenoid natural product. The evolution of our strategy was defined by the unique chemistry of the mutilin tricyclic scaffold, and relied on an oxidative ring-expansion of a tetracyclic precursor that was assembled by a cycloaddition-radical cyclization approach. The completed synthesis is the shortest reported to date and proceeded with complete stereochemical relay throughout the sequence. 

Ion Transport Gating in Hydrophobic Nanopores

Abstract: Studying ion transport in nanoporous materials is crucial to a wide range of energy and environmental technologies, including ion-selective membranes, drug deliver systems, and supercapacitors. Hydrophobic nanoporous materials are of great research interest due to their ability to act as nanoscale valves, preventing the transport of liquid water in the absence of external stimulation. Commercial industries have already taken advantage of this phenomenon, making breathable fabrics that allow sweat to evaporate but keep liquid water from penetrating the material.

Understanding the Steric and Electronic Factors that StabilizeTh(III), Th(II), and U(II) Complexes

Abstract:

This talk will discuss various attempts to synthesize low-valent thorium and uranium complexes with cyclopentadienyl ligands in an effort to better our understanding at what factors are important for stabilizing low-valent actinide complexes.  Synthetic, spectroscopic, crystallographic, and theoretical data will be presented.

Development of Nickel-Catalyzed Cross-Coupling, Cross-Electrophile Coupling and Domino Reactions

Abstract: The world around us, from the medicines we take, to the food we eat, to the plants and animals surrounding us, is composed of carbon-carbon (C–C) bonds. In order to construct these C–C bonds, we rely on previously developed methodologies. In an ever growing world, the need for new technologies to tackle more challenging problems has grown significantly. Catalysis has emerged in the last century as a reliable, efficient and sustainable method to synthesize C-C bonds.

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