Development of radical processes triggered by the photochemical activity of transient organic intermediates

Identifier:  TDX:2721

Handle: https://hdl.handle.net/20.500.11797/TDX2721

Authors:  Filippini, Giacomo

Abstract:
The chemistry developed during my doctoral thesis was driven by the ability of electron rich intermediates (phenolate anions and chiral enamines), transiently generated from photochemically inactive precursors (phenols and aldehydes), to directly reach an electronically excited state upon light absorption and subsequently promoting the formation of reactive radical species from suitable alkyl iodides. In the studied transformations, the radicals are formed through the reductive cleavage of the carbon-iodine bond within the alkyl iodide precursor via single-electron transfer (SET) mechanisms. Initially, I developed a new approach for the photochemical direct perfluoroalkylation of substituted phenols. The use of simple visible light, without the need of any photocatalyst or radical initiator, can promote an aromatic perfluoroalkylation or trifluoromethylation of phenols at ambient temperature. In a second project, I developed a new methodology for the enantioselective formal α-methylation and α-benzylation of aldehydes by means of photo-organocatalysis. The reaction occurs in the absence of external photoredox catalysts, and the desired compounds were obtained in good isolated yields with high enantioselectivity.