Palladium-catalyzed C–H glycosylation and retro Diels–Alder tandem reaction via structurally modified norbornadienes (smNBDs) |
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| Authors: | Yang An Bo-Sheng Zhang Ya-Nan Ding Zhe Zhang Xue-Ya Gou Xue-Song Li Xiaolei Wang Yuke Li Yong-Min Liang |
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| Institution: | State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 P. R. China.; College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou Gansu 730070 P. R. China ; Department of Chemistry, Centre for Scientific Modeling and Computation, Chinese University of Hong Kong, Shatin, Hong Kong P. R. China, |
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| Abstract: | This report describes palladium-catalyzed C–H glycosylation and retro Diels–Alder tandem reaction via structurally modified norbornadienes (smNBDs). smNBDs were proposed to regulate the reactivity of the aryl-norbornadiene-palladacycle (ANP), including its high chemoselectivity and regioselectivity, which were the key to constructing C2 and C3 unsubstituted C4-glycosidic indoles. The scope of this substrate is extensive; the halogenated six-membered and five-membered glycosides were applied to the reaction smoothly, and N-alkyl (primary, secondary and tertiary) C4-glycosidic indoles can also be obtained by this method. In terms of mechanism, the key ANP intermediates characterized by X-ray single-crystal diffraction and further controlled experiments proved that the migration-insertion of smNBDs with phenylpalladium intermediate endows them with high chemo- and regioselectivity. Finally, density functional theory (DFT) calculation further verified the rationality of the mechanism.This report describes palladium-catalyzed C–H glycosylation and retro Diels–Alder tandem reaction via structurally modified norbornadienes (smNBDs). |
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