Esken Robin, Antoni Patrick W, Lorenz Yannick, Burdenski Chris, Kirchhoff Jan-Lukas, Strohmann Carsten, Hansmann Max M
Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany.
Angew Chem Int Ed Engl. 2025 Jul;64(29):e202506305. doi: 10.1002/anie.202506305. Epub 2025 May 19.
The synthesis of polarized N-heterocyclic olefins (NHOs) based on an imidazo[1,5-a]pyridine scaffold is presented. In contrast to regular NHOs the unique bicyclic heterocyclic core allows the incorporation of various substituents in close proximity to the highly polarized exocyclic C─C bond. The donor properties of the new carbon-based ligand class were quantified and the coordination chemistry explored. Alkenyl or alkynyl groups at the C5-position lead to spontaneous cyclization to yield imidazo[2,1,5-de]quinolizines. The unique cyclization strategy was compatible with a wide range of substitution patterns and yields highly electron-rich π-delocalized heterocycles. The electronic structure of the novel partially antiaromatic heterocycle was thoroughly investigated. One-electron oxidation occurs at low potentials and lead to a stable monomeric radical-cation confirmed by XRD, which showed solution phase fluorescence expanding into the field of open-shell organic materials.
本文介绍了基于咪唑并[1,5-a]吡啶骨架的极化N-杂环烯烃（NHOs）的合成。与常规NHOs不同，独特的双环杂环核心允许在紧邻高度极化的环外C─C键处引入各种取代基。对新型碳基配体类别的给体性质进行了量化，并探索了其配位化学。C5位的烯基或炔基会导致自发环化，生成咪唑并[2,1,5-de]喹嗪。这种独特的环化策略与广泛的取代模式兼容，并能产生高度富电子的π-离域杂环。对新型部分反芳香性杂环的电子结构进行了深入研究。单电子氧化在低电位下发生，并产生一个稳定的单体自由基阳离子，XRD证实了这一点，该自由基阳离子在溶液相中的荧光扩展到了开壳有机材料领域。
