Designer Dithiocarbamates as Radical Covalent Catalysts via Excited-State Triplet Biradicals: Application to Skeletal Reorganization of Vinylaziridines

A reactivity of dithiocarbamates as radical covalent catalysts was unveiled through the development of modular thiazole-2-thiones for achieving a skeletal reorganization of <i>N</i>-sulfonyl vinylaziridines to the corresponding aminocyclopentanes with adjacent vinyl appendages under visible-light irradiation. Based on the initial findings on the ability of thiazole-2-thione radical cations to act as robust catalysts, pertinent structural modifications of the thiazole-2-thione enabled its excited-state triplet biradical, formed via energy transfer from an iridium-based photocatalyst, to exert high catalytic activity. This system offers a reliable tool for straightforward access to various aminocyclopentanes, which are important components of a range of bioactive molecules and pharmaceuticals. A series of experimental and computational mechanistic investigations underpinned a predominant pathway that involves the triplet biradical as a catalytically active species viable to engage in the covalent activation of vinylaziridine for the ensuing radical cascades. This study sheds light on the potential of excited-state triplet biradicals as radical covalent catalysts, providing a strategy for expanding this promising field of research.