Kumada-Tamao-Corriu Coupling of Alkyl Halides Catalyzed by an Iron-Bisphosphine Complex

An iron(II) chloride complex possessing a sterically demanding ortho-phenylene-tethered bisphosphine ligand shows a high catalytic activity in the Kumada-Tamao-Corriu coupling of nonactivated alkyl halides with aryl Grignard reagents. Primary, secondary, and tertiary alkyl halides can participate as an electrophilic coupling partner. A radical clock experiment using (iodomethyl)cyclopropane exclusively gives the corresponding ring-opening coupling product, suggesting intermediacy of alkyl radical species.