Unlocking Tertiary Acids for Metallaphotoredox C(sp(2))-C(sp(3)) 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 a-carbons, a valuable but challenging substrate class for C(sp(2))-C(sp(3)) 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.