Ketyl Radical Coupling Enabled by Polycyclic Aromatic Hydrocarbon Electrophotocatalysts

Abstract

Herein, we report a new class of electrophotocatalysts, polycyclic aromatic hydrocarbons, that promote the reduction of unactivated carbonyl compounds to generate versatile ketyl radical intermediates. This catalytic platform enables previously challenging intermolecular ketyl radical coupling reactions, including those that classic reductants (e.g., SmI2/HMPA) have failed to promote. More broadly, this study outlines an approach to fundamentally expand the array of reactive radical intermediates that can be generated via electrophotocatalysis by obviating the need for rapid mesolytic cleavage following substrate reduction.

Photochemical dearomative skeletal modifications of heteroaromatics

“…As an efficient way to construct enantioselective sp 3 rich heterocycles from heteroarenes, the cooperative photoredox- and bio-catalysed dearomatization may be desirable, but research in this field is limited by the generality and feasibility. Finally, considering the broad redox potential spectrum, electrophotochemistry 145,146 is expected to harness its unique strength in the dearomatization of inert heteroarenes.…”

Electrophotoredox cerium-catalyzed decarboxylative radical cyclization cascade for the synthesis of alkylated benzimidazo-fused isoquinolinones

“…Electrophotocatalysis has expanded the synthetic chemists' toolbox to generate and manipulate radical species under mild conditions. 1–8 In particular, electrophotocatalysis enables the transformation of redox mediators into strongly oxidizing or reducing species 9–13 that cannot be provided by the electrolysis alone (Scheme 1a). 14–18 The electrophotochemically triggered extreme redox abilities of these mediators provide the basis for the activation of substrates with high redox potentials via single-electron transfer (SET) pathways.…”

Synthesis of Alcohols: Streamlined C1 to Cn Hydroxyalkylation through Photoredox Catalysis

“…1, C, path b). 17 Furthermore, Nagib presented a redox-neutral generation of ketyl radicals through in situ conversion of aldehydes to α-acetoxy iodides followed by Mn-catalyzed atom transfer under visible light irradiation. 8 A complementary method for accessing α-hydroxy radicals involves the C-H abstraction from alcohols through visible light-promoted hydrogen atom transfer (HAT) (Fig.…”