Developing and Exploiting New Photoreductants in Radical Chemistry

Identifier:  TDX:4555

Handle: https://hdl.handle.net/20.500.11797/TDX4555

Authors:  Wu, Shuo

Abstract:
The work carried out in this doctoral thesis has identified new organic catalysts or intermediates that, upon excitation with visible light, could access a highly reducing excited state and subsequently act as potent single-electron transfer reductants to activate a diverse range of inert compounds towards radical formation. In Chapter II, we developed a photochemical catalytic platform for activating diverse inert substrates. The key discovery was identifying a simple indole thiolate organocatalyst that, upon deprotonation and light excitation, becomes a powerful reductant. This light-driven catalytic platform exhibited broad generality, effectively enabling the reductive activation of inert chemical substrates. Chapter III explores the photochemical synthesis of thioethers using readily accessible aryl chlorides and alcohols as feedstocks—without the need for thiols or transition metals. Leveraging our indole thiolate organic photocatalyst, we achieved the cleavage of C(sp²)-Cl bonds to generate aryl radicals. These radicals are subsequently captured by tetramethylthiourea, forming an aryl isothiouronium intermediate. This intermediate then undergoes ionic dexythiolation pathway with alkyl alcohols, resulting in the formation of aryl alkyl thioethers. Chapter IV introduces a novel photochemical approach for synthesizing thioesters from readily available aryl halides and carboxylic acids.