Engaging Tertiary Benzylic Radicals in Metallaphotoredox Catalysis: A Modular Approach to Access Diaryl Quaternary Centers

Herein we report the decarboxylative cross-coupling of tertiary benzylic carboxylic acids and aryl bromides to furnish all-carbon diaryl quaternary centers. For the first time, tertiary benzylic radicals are introduced as viable participants in metallaphotoredox-catalyzed cross-couplings by suppressing undesired benzylic radical dimerization via fast radical trapping with Cu. We demonstrate the functionalization of feedstock carboxylic acids as well as late-stage functionalization of carboxylic acid-containing drugs.