Agata J. Pacuła‐Miszewska, Magdalena Obieziurska‐Fabisiak, Jacek Ścianowski
Background/Objectives: Natural metabolites, due to their abundance, structural diversity, and availability in enantiomerically pure form, are broadly utilized in the synthesis of reagents, catalysts, building blocks, and potential therapeutics. To date, various organoselenium compounds, including selenides, diselenides, selenols, selenonium salts, and ylides, have been created based on the scaffold of primary and secondary metabolites like amino acids, sugars, nucleic bases, terpenes, and steroids. Their synthesis and application routes as reagents and catalysts in organic synthesis and biological systems are summarized in the presented review. Methods: The gathered material has been divided into two sections—naturally derived organoselenium compounds, such as antioxidants and GPx-mimetics, and reagents utilized in modern organic transformations. Results: The review summarizes the utility of natural scaffolds in the construction of organoselenium compounds with promising applications as antioxidant-type catalysts in biological systems (GPx-mimetics) and potent reagents for organic transformations, including asymmetric reactions. Conclusions: This review provides a comprehensive overview of known organoselenium reagents derived from natural compounds, discusses the advantages of their use in medicinal chemistry and modern organic synthesis, and outlines prospective directions for future development in this area.