Palladium-Catalyzed Diastereo- and Enantioselective [3 + 2] Cycloaddition of Vinylcyclopropanes with Azadienes:
Kai Liu1, Jianfeng Yang1, Xiaoxun Li1,2
1Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China.
Abstract:
Benzofuran-derived azadienes (BDAs) have been widely used as four-atom synthons in transition-metal-mediated cycloaddition reactions, while the exploitation of their reactivity as a two-atom unit to construct spirocycles is still underdeveloped. Herein, we reported the first palladium(0)-catalyzed diastereo- and enantioselective [3 + 2] annulation of vinylcyclopropanes (VCPs) and BDAs. This transformation is featured with a broad substrate scope (31 examples), allowing for facile access to a variety of enantioenriched spirocycles bearing a quaternary stereogenic center in good yields with excellent regio-, diastereo-, and enantioselectivities (up to 93% yield, >20:1 dr, and mostly >99% ee) under mild reaction conditions. Moreover, the spirocyclic products could be efficiently converted to structurally complex tricyclo[8.3.0.01,5]-azatridecane and tricyclo[7.3.0.01,5]-azadodecane skeletons.
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