Ni-Catalyzed Reductive Dicarbofunctionalization of Nonactivated Alkenes: Scope and Mechanistic Insights

Olefins devoid of directing or activating groups have been dicarbofunctionalized here with two electrophilic carbon sources under reductive conditions. Simultaneous formation of one C­(sp3)–C­(sp3) and one C­(sp3)–C­(sp2) bond across a variety of unbiased π-systems proceeds with exquisite selectivity by the combination of a Ni catalyst with TDAE as sacrificial reductant. Control experiments and computational studies revealed the feasibility of a radical-based mechanism involving, formally, two interconnected Ni­(I)/Ni­(III) processes and demonstrated the different ability of Ni­(I) species (Ni­(I)I vs PhNi­(I)) to reduce the C­(sp3)–I bond. The role of the reductant was also investigated in depth, suggesting that a one-electron reduction of Ni­(II) species to Ni­(I) is thermodynamically favored. Further, the preferential activation of alkyl vs aryl halides by ArNi­(I) complexes as well as the high affinity of ArNi­(II) for secondary over tertiary C-centered radicals explains the lack of undesired homo- and direct coupling products (Ar–Ar, Ar–Alk) in these transformations.