Development of Radical Processes Triggered by the Photochemical Activity of Transient Organic Intermediates

The chemistry discussed within the doctoral thesis of the candidate, Giacomo Filippini, elucidates the ability of electron-rich organic molecules (phenolate anions and chiral enamines), transiently generated from photochemically inactive precursors (phenols and aldehydes), to directly reach, upon light absorption, an electronically excited state in order to trigger the formation of reactive radical species. This occurs through the reductive cleavage of the carbon-iodine bond of the corresponding alkyl iodide precursor, via a single-electron transfer (SET) pathway. First, a novel photochemical strategy for the direct perfluoroalkylation of substituted phenols is described. This approach uses simple visible light, in the absence of photocatalyst or radical initiator, to promote aromatic perfluoroalkylation and trifluoromethylation reactions of phenols under mild conditions. Subsequently, the development of a photo-organocatalytic enantioselective methodology for the formal α-methylation and α-benzylation of aldehydes is discussed. As the previous strategy, this approach does not require the use of external photoredox catalysts and delivers the desired α-alkylated products in high yield and enantioselectivity.