Decarboxylative C(sp ² )−C(sp ³ ) Cross-Coupling of Bicyclo[1.1.1]pentane and Cubane Carboxylic Acids Using a Nickel(II) Aryl Precatalyst

Metallaphotoredox conditions employing an iridium photocatalyst and a nickel(II) oxidative addition complex as a precatalyst have been developed for the elusive direct decarboxylative C(sp2)−C(sp3) cross-coupling of bicyclo[1.1.1]pentane carboxylic acids and cubane carboxylic acids with (hetero)aryl halides. The substrate scope is broad, and the reaction is applicable to late-stage functionalization of complex, pharmaceutically relevant substrates. NMR experiments provide insight into how the nickel(II) oxidative addition complex enters the catalytic cycle and suggest that it achieves the proposed catalyst resting state more efficiently than a more commonly used ligated nickel(II) bromide salt. This study establishes the utility of a catalytic nickel(II) oxidative addition complex for metallaphotoredox method development for carbon-carbon bond formation and demonstrates the ability of cubane carboxylic acids to engage directly in C(sp2)−C(sp3) cross-coupling.