Ferrioxalate photocatalysis: A multitasking platform for reductive iron catalysis

Iron's abundance motivates its use in sustainable catalyst systems that also offer complementary reactivity manifolds compared to precious metals. However, the challenging reduction of benchmark iron salts to active species hinders their application in reductive transformations. In this work, we report a photochemical strategy that exploits the innate reactivity of ligand-to-metal charge transfer (LMCT) excited states of iron oxalate complexes to harness oxalate salts as latent terminal two-electron reductants in iron catalysis. The investigation of this activation mode has led to the development of a versatile catalytic platform enabling transformations hitherto inaccessible to previous iron catalyst systems. The synthetic value of this tactic is demonstrated on diverse reductive transformations using readily available building blocks with high chemoselectivity, opening new synthetic opportunities.