Iminyl radical-triggered relay annulation for the construction of bridged aza-tetracycles bearing four contiguous stereogenic centers |
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Authors: | Kun Jiang Shi-Jun Li Qing-Peng Liu Ning Yu Yu-Lin Li Yu-Qiang Zhou Kui-Cheng He Jing Lin Ting-Yu Zheng Jian Lang Yu Lan Ye Wei |
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Institution: | School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 China.; College of Chemistry, Institute of Green Catalysis, Zhengzhou University, Zhengzhou Henan 450001 China, |
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Abstract: | Bridged tetracyclic nitrogen scaffolds are found in numerous biologically active molecules and medicinally relevant structures. Traditional methods usually require tedious reaction steps, and/or the use of structurally specific starting materials. We report an unprecedented, iminyl radical-triggered relay annulation from oxime-derived peresters and azadienes, which shows good substrate scope and functional group compatibility, and can deliver various bridged aza-tetracyclic compounds with complex molecular topology and four contiguous stereogenic centers (dr > 19 : 1) in a single operation. This transformation represents the first example of trifunctionalization of iminyl radicals through simultaneous formation of one C–N and two C–C bonds. DFT calculation studies were conducted to obtain an in-depth insight into the reaction pathways, which revealed that the reactions involved an interesting 1,6-hydrogen atom transfer process.A novel radical relay annulation is realized for the construction of various bridged aza-tetracyclic compounds with complex molecular topology and four contiguous stereogenic centers (dr > 19 : 1) in a single operation. |
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