Visible light mediated reductions of ethers, amines and sulfides

• Method for the reduction of α-keto ethers amines and sulfides at room temperature using visible light and an Ir(III) photocatalyst.
• Reactions run in ethanol with minimal additive loadings.
• Lignin model substrates containing the β–O–4 motif were reduced in fair to good yields.

Visible light-mediated photoredox catalysis enables the chemoselective reduction of activated carbon–heteroatom bonds as a function of reduction potential. The expansion of the scope of C–X bond reductions towards less activated motifs, such as ethers, amines and sulfides, is important to both organic synthesis and macromolecular degradation method development. In the present report, exploration of photoredox catalysis in alcoholic solvents mediated a decrease in the super-stoichiometric use of iPr2NEt and HCO2H in the reduction of α-keto ethers, amines and sulfides. Additionally, in the absence of fragmentation, CC bond formation was afforded, suggesting an intermediate ketyl radicals are present in these transformations.

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