Bioinspired Carbon Radical Catalysis

Carbon radicals are fundamental and pivotal intermediates found in a veritable cornucopia of applications in diverse chemical contexts. Although nature elegantly employs them in enzymes like adenosylcobalamin (AdoCbl) for hydrogen atom transfer catalysis via dynamic cobalt-carbon covalency, their synthetic application in laboratory settings has been stymied by a fundamental paradox: transient radicals form irreversible bonds, while persistent radicals are catalytically inert. Inspired by AdoCbl, we report a catalytic system that circumvents this limitation through the reversible homolysis of a tailored dimer with a dynamic C(sp³)-C(sp³) bond. This mechanism allows the nascent carbon radical to interact reversibly with vinyl cyclopropanes, facilitating subsequent irreversible [3 + 2] reactions with alkenes and the regeneration of active catalyst. The power of this approach is demonstrated in a highly efficient and modular synthesis of cis-cyclopentanes, offering opportunities to rapidly access complex architectures and novel chemical spaces for lead discoveries.