Unlocking Tertiary Acids for Metallaphotoredox C(sp2)-C(sp3) Decarboxylative Cross-Couplings

Dual nickel photoredox catalysis conditions have been developed for the decarboxylative cross-coupling of aryl halides and carboxylic acids containing fully substituted alpha carbons, a valuable but challenging substrate class for C(sp2)–C(sp3) bond-forming reactions. High-throughput experimentation identified Ni(TMHD)2 as the optimal precatalyst for this reaction in contrast to the nickel-bipyridyl complexes typically employed in decarboxylative couplings, which predominantly furnished undesired C–O products. Computational work provides insight into the potential mechanistic underpinnings for the C–C vs. C–O selectivity for the nickel-diketonate complex.