关键词: 环状N-磺酰基醛亚胺, [1.1.1]螺桨烷, 磺酰化, 光诱导, 电子供体-受体复合物

Herein, we report a visible-light-induced difunctionalization of [1.1.1]propellane via an electron donor-acceptor (EDA) complex, enabling selective 1,3-sulfonylation/heteroarylation with cyclic N-sulfonyl aldimines and sulfonyl chlorides. This protocol provides an efficient route to 1-sulfonyl-3-heteroaryl bicyclo[1.1.1]pentanes (BCPs), rigid three-dimensional scaffolds valuable as bioisosteric substitutes for para-substituted arenes in drug discovery. Under standard conditions, the desired products were obtained in moderate to excellent yields. This transformation operates under visible light at room temperature without transition-metal catalysts or external photosensitizers. The EDA complex serves as the pivotal intermediate; upon photoexcitation, it triggers single-electron transfer to generate sulfonyl radicals and radical anions, initiating a cascade that constructs both C-S and C-C bonds at the bridgehead positions. This unique mechanism avoids precious metal usage and suppresses side reactions typical of UV or thermal conditions. Optimization studies identified triethylamine as the preferred base, 1,2-dichloroethane as the optimal solvent, 405 nm as the best light source, and 6 hours as the ideal reaction time. In a typical procedure, a nitrogen-purged Schlenk tube charged with cyclic N-sulfonyl aldimine (0.2 mmol), p-toluenesulfonyl chloride (0.3 mmol), [1.1.1]propellane (0.3 mmol), and triethylamine (0.4 mmol) in DCE (2 mL) is irradiated at 405 nm for 6 hours. Purification by column chromatography affords the corresponding products. The substrate scope was systematically examined, covering various cyclic N-sulfonyl aldimines and sulfonyl chlorides bearing pharmaceutically relevant groups. Scale-up reactions delivered comparable results, and subsequent derivatizations converted BCP products into diverse architectures, illustrating synthetic utility. Mechanistic studies, including radical trapping and UV-vis spectroscopy, confirmed radical intermediates and EDA complex formation. Based on these findings, a plausible pathway is proposed: photoinduced electron transfer, sulfonyl radical generation, regioselective addition to [1.1.1]propellane, and radical trapping to forge the C-heteroaryl bond. Collectively, this work offers a mild, sustainable, and scalable approach to functionalized BCPs, enriching the medicinal chemistry toolbox with sp³-rich building blocks.

Key words: cyclic N-sulfonyl aldimines, [1.1.1]propellane, sulfonylation, visible-light-induced, EDA complex