Iron/photoredox dual-catalyzed redox-neutral double decarboxylative C(sp3)–C(sp3) cross-coupling

Abstract

As enzyme mimics, metal porphyrin complex catalysts have become increasingly powerful for facilitating alkyl radical transformations. This report describes an iron porphyrin/photoredox catalytic manifold that enables the heteroselective assembly of sp³-hybridized carbon frameworks from diverse aliphatic carboxylic acids. The double decarboxylative cross-coupling reaction features mild and redox-neutral conditions, good functional group tolerance, and high heteroselectivity. Due to their opposing redox characteristics, photoredox-mediated electron shuttling between carboxylic acids and NHPI esters provides ready access to distinct alkyl radicals in the absence of external oxidants or reductants. The iron porphyrin-catalyzed radical-sorting S_H2, evidenced by mechanistic studies, is proposed to be responsible for the highly selective radical–radical heterocoupling.