Date of Award
Doctor of Philosophy (PhD)
Gary A. Molander
In the past decade, renewed interest in odd-electron pathways has reaffirmed organic chemistry’s indispensable role in the synthesis of complex molecules and in drug-discovery efforts. Odd-electron intermediates unlock reactivity patterns that are not observed in two-electron processes and offer complementary chemoselectivity. Importantly, these processes are often “blind” to the source of radical and can thus be adapted toward a diverse array of chemical feedstocks. Photoredox catalysis harnesses radicals in a controlled, predicable manner and can be used to orchestrate elaborate radical and polar bond-forming processes, which allowed the development of the radical-polar crossover annulation reaction (RPAR) paradigm. Furthermore, these catalysts, in conjunction with transition metal complexes, enable multiple C-C bond-forming events in so-called dicarbofunctionalization (DCF) reactions, and can even be used to functionalize commodity materials via photochemical C-H abstraction. Visible light can also be used to excite electron donor-acceptor complexes in the absence of a photocatalyst to permit radical generation. This mode of reactivity has provided an avenue to new bioisosteric space via the late-stage introduction of bicyclo[1.1.1]pentyl (BCP) motifs. Finally, photochemically-initiated hydrogen-atom transfer (HAT) catalysis can be harnessed to access strong single-electron reductants that permit the single C-F bond activation of trifluoroacetates and -acetamides. This has allowed facile access to gem-difluoromethylene containing compounds that are challenging to prepare by state-of-the-art methods. Discoveries in each of these arenas will be discussed.
Polites, Viktor Christian, "Unlocking New Odd-Electron Pathways Via Photoactive Catalysis" (2022). Publicly Accessible Penn Dissertations. 5614.
Additional FilesPolites_NMR_spectra.pdf (39275 kB)