Pd(0)/Blue Light Promoted Carboiodination Reaction – Evidence for Reversible C–I Bond Formation via a Radical Pathway

A Pd(0)/blue light catalyzed carboiodination reaction is reported. A simple, air-stable catalytic system, utilizing [Pd(allyl)Cl]₂ and DPEPhos, generated a variety of iodinated hetero- and carbocycles including oxindoles, dihydrobenzofurans, indolines, a chromane, and a tetrahydronaphthalene. This protocol was tolerant of sensitive functional groups including free carboxylic acids, phenols, and anilines, as well as pyridines, while delivering products in up to 94% yield. Support for a reversible C-I bond formation via a single electron mechanism was obtained using a deuterium labeled substrate and a stoichiometric neopentylpalladium species.