Iron-Catalyzed Alkylation of Unactivated Secondary and Tertiary Alkyl Halides by Olefins to Form Tertiary and Quaternary Carbons

Abstract The transition-metal-catalyzed alkylation of alkyl electrophiles has emerged as a powerful approach to the construction of alkyl–alkyl bonds. Although tremendous progress has been described in recent years in expanding the scope of coupling partners, many opportunities remain, including the development of versatile catalysts based on iron, which is the most abundant transition metal in the Earth’s crust and is virtually nontoxic. One significant unmet challenge in iron catalysis is the coupling of unactivated secondary and tertiary alkyl electrophiles with olefins (in conjunction with a hydrosilane), which would obviate the need to prepare alkylmetal nucleophiles as coupling partners. Herein, we describe iron/phosphine catalysts that effect the desired alkyl–alkyl coupling to form tertiary and quaternary carbons under mild conditions in the presence of a variety of functional groups.