Semiheterogeneous Intrinsic CoS 2 -Photoredox/Cp 2 Fe Dual-Catalyzed Synthesis of Selenylated Phenanthrene

Herein, we report a practical semiheterogeneous strategy for the photosynthesis of diverse selanyl phenanthrenes, employing CoS₂ as a heterogeneous photocatalyst in combination with ferrocene (Cp₂Fe) as a homogeneous redox catalyst. This synergistic system combines photogenerated electron-mediated reduction of selenyl cations into diselenide with photogenerated hole oxidation of Cp₂Fe to its oxidized form, which not only oxidizes diselenide into selenyl radicals but also mediates oxidative dehydroaromatization, leading to high-yielding transformations with broad functional group compatibility. Notably, this method eliminates the need for stoichiometric oxidants or reductants and avoids sacrificial electron donors or acceptors.