Copper-catalyzed alkyne oxidation/Büchner-type ring-expansion to access benzo[6,7]azepino[2,3-b]quinolines and pyridine-based diones

作者：Xiao‐Lei Jiang, Qing Liu, Kua‐Fei Wei, Tingting Zhang, Guang Ma, Xiu-Hong Zhu, Guang-Xin Ru, Lijie Liu, Lianrui Hu, Wen‐Bo Shen · 发表于：Communications Chemistry · 年份：2023 · DOI：10.1038/s42004-023-00840-6 · 被引用次数：12 · 研究领域：Catalytic Alkyne Reactions、Catalytic C–H Functionalization Methods、Oxidative Organic Chemistry Reactions

General access to highly valuable seven-membered rings via Büchner-type reaction remains a formidable challenge. Here we report a Cu-catalyzed intermolecular oxidation of alkynes using N-oxides as oxidants, which enables expedient preparation of valuable benzo[6,7]azepino[2,3-b]quinolines and pyridine-based diones. Importantly, in contrast to the well-established gold-catalyzed intermolecular alkyne oxidation, the dissociated pyridine or quinoline partner could be further utilized to construct N-heterocycles in this system and the reaction most likely proceeds by a Büchner-type ring expansion pathway. A mechanistic rationale for this cascade cyclization is supported by DFT calculations.