Modular Cyano-fluoroalkylation of Unactivated Alkenes Enabled by Photoinduced Fe-LMCT Catalysis

The radical 1,2-difunctionalization of alkenes represents a powerful strategy for the rapid assembly of complex, sp3-rich scaffolds from simple alkene feedstocks. Herein, we describe the implementation of an iron photocatalyzed cyano-fluoroalkylation of unactivated alkenes that leverages inexpensive trifluoroacetic acid (CF3CO2H) and related carboxylic acids (CFnRCO2H) as radical fluoroalkyl sources, together with tosyl cyanide (TsCN) as a low-toxicity cyanation reagent. The transformation is enabled by photoinduced ligand-to-metal charge transfer (LMCT) within [FeIII]-O2CCFnR complexes, which generate fluoroalkyl radicals (•CFnR) under visible-light irradiation while triggering a three-component radical process. Notably, the mild and redox-neutral conditions of the method are compatible with a broad range of substrates, including alkenes containing biologically relevant motifs (40 examples, up to 83% yield). The synthetic utility of the resulting β-fluoroalkylated nitrile products is demonstrated through diverse derivatizations, providing straightforward access to other valuable fluorinated sp3-rich architectures. On the other hand, mechanistic studies have revealed the key role of a protonated bypiridine-based ligand in enhancing reaction efficiency.