Cross-Electrophile Coupling via Iron-Mediated Tandem S-_N2/S_H2-Type Reaction

Keywords

iron catalysis - iridium photocatalysis - cross-electrophile coupling

Significance

MacMillan and colleagues report the cross-electrophile coupling of tertiary bromides and primary alkyl electrophiles using iron catalysis. By harnessing an iron(I)-mediated S_N2 reaction of alkyl electrophiles, followed by a bimolecular homolytic substitution (S_H2) reaction with in situ generated tertiary radical species, a variety of molecules bearing a quaternary center can be synthesized. The authors demonstrate that a range of alkyl bromides and alkyl sulfonates can effectively participate in the coupling reaction.

 

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Comment

In-depth mechanistic studies are reported, including variable time normalization analysis, which provides insights into the kinetic orders of the reaction components. Photonuclear magnetic resonance studies confirm the intermediacy of Fe(I) and Fe(III) complexes under the reaction conditions. Notably, the detection of Fe(I) before the Fe(III) complex supports the proposal that the formation of Fe(I) is a crucial step for the subsequent formation of the Fe(III)–alkyl complex through an S_N2-type pathway.

 

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Publikationsverlauf

Artikel online veröffentlicht:
28. Januar 2025