Effective Alkyl‐Alkyl Cross‐Coupling with an Iron‐Xantphos Catalyst: Mechanistic and Structural Insights.

While iron‐catalyzed C(sp2)−C(sp3) cross‐couplings have been widely studied and developed in the last decade, alkyl‐alkyl cross‐coupling systems with iron remain underdeveloped despite the importance of C(sp3)−C(sp3) bonds in organic synthesis. A major challenge to the development of these reactions is the current lack of fundamental insight into ligand effects and organoiron intermediates that enable effective alkyl‐alkyl couplings. The current study addresses this longstanding limitation using a combination of 57Fe Mössbauer spectroscopy, SC‐XRD (single‐crystal X‐ray diffraction) and reactivity studies of alkyl‐alkyl coupling with iron‐Xantphos to define the in situ formed iron‐Xantphos intermediates in catalysis. Combined with detailed reactivity studies, the nature of the key mechanistic pathways in catalysis and ligands effects to achieve effective alkyl‐alkyl cross‐coupling over competing β‐H elimination pathways are probed. Overall, these foundational studies provide a platform for future bespoke ligand and pre‐catalyst design for alkyl‐alkyl cross‐coupling methods development with sustainable iron catalysis. [ABSTRACT FROM AUTHOR]