Wu, Tianrui, Castro, Anthony, Ganguli, Kasturi, Ye, Ning, Gallou, Fabrice, Wu, Bin-3 and Weix, Daniel (2025) Cross-Electrophile Coupling to form Sterically Hindered C(sp2)-C(sp3) Bonds: Ni and Co Afford Complementary Reactivity. Journal of the American Chemical Society JACS..

Abstract

The formation of sterically hindered C(sp2)−C(sp3)
bonds could be a useful synthetic tool but has been understudied in
cross-electrophile coupling. Here, we report two methods that
couple secondary alkyl bromides with aryl halides that contain
sterically hindered C−X bonds: 1) ortho-substituted aryl bromides
with nickel catalysts and 2) di-ortho-substituted aryl iodides with
cobalt catalysts. Stoichiometric experiments and deuterium labeling
studies show that 1) [Co] is better than [Ni] for oxidative addition
of di-ortho-substituted Ar−I and 2) [Co] is better than [Ni] for
radical capture/reductive elimination steps with di-ortho-substituted arenes. For both metals, Ar−H side products observed in
reactions with low-yielding di-ortho-substituted aryl iodides appear to arise from Ar• formation and hydrogen-atom transfer from the
solvent. While the origins of the differences in scope are not yet understood, these studies demonstrate a previously unknown
complementarity between nickel and cobalt in cross-electrophile coupling.

Item Type:	Article
Date Deposited:	21 Mar 2025 00:45
Last Modified:	21 Mar 2025 00:45
URI:	https://oak.novartis.com/id/eprint/55193