Oxygen‐Radical Capture Enabled Nickel‐Catalyzed Carbon(sp ² )‐Heteroatom Coupling of Two Nucleophiles

Abstract

ABSTRACT Hypervalent transition‐metal complexes serve as pivotal intermediates enabling reductive elimination for carbon–heteroatom bond formation. Significant efforts have focused on nickel‐catalyzed couplings of aryl (pseudo)halides with nucleophiles, utilizing, for example, photo‐ or electrochemical strategies to access high‐valent Ni(III) species. Nevertheless, the analogous Ni(III)‐mediated oxidative cross‐coupling of two nucleophilic partners for carbon–heteroatom bond construction remains elusive, despite the central role of such nucleophiles, for example, boronic acids, in cross‐coupling chemistry. Herein, we report a general oxygen‐radical capture strategy that accelerates the single‐electron oxidation of Ni(II) and subsequent reductive elimination, enabling diverse carbon–heteroatom bond formations with aryl boronic acids. We demonstrate the oxidative coupling of aryl boronic acids with alcohols, a transformation that has never been realized by nickel catalysis, likely due to the facile β‐hydride elimination of the corresponding metal alkoxides. Mechanistic investigations and DFT calculations suggest the crucial role of the tert ‐butoxyl radical in the transformation of Ni(II) to Ni(III), enabling facile reductive elimination that bypass other possible side pathways. Furthermore, we show that a broad range of nucleophiles can be employed for the construction of C–O, C–S, C–N, and C–P bonds using this method.