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2篇 您的检索式:作者名="Cefei Zhang"
    题名 作者 年代 出处 被引量
1New chiral N-heterocyclic olefin bifunctional organocatalysis inα-functionalization ofβ-ketoesters显示文摘N-heterocyclic olefins(NHOs)possess an electron-rich and highly polarized C=C double bond due to the donating property of nitrogen atoms.This feature imparts exocyclic carbon atom of NHOs with strong basicity and high nucleophilicity.Although NHOs have been emerging as a new type of organocatalyst and ligand for metal complexes in organic synthesis,chiral NHOmediated highly enantioselective organic transformations were still elusive.Herein,we developed a new type of chiral aminederived C_(2)-symmetric NHOs and employed them as efficient chiral bifunctional organocatalysts for asymmetricα-functionalization ofβ-ketoesters.With as low as 0.1 mol%catalyst loading,the desired amination and trifluoromethylthiolation products were afforded in good yields with high enantioselectivities(up to 99%yield and 99%ee).Experimental studies and theoretical calculation disclosed that hydrogen-bonding interaction upon protonation and other weak interaction between substrate and catalyst were crucial for the enantiocontrol.Sijing Wang Cefei Zhang Da Li Yuqiao Zhou Zhishan Su Xiaoming Feng Shunxi Dong 2023Science China Chemistry2023,66,1:0
2Chiral nickel(Ⅱ) complex catalyzed asymmetric(3+2) cycloaddition ofα-diazo pyrazoleamides with 2-siloxy-1-alkenes显示文摘A highly efficient asymmetric(3 + 2) cycloaddition of α-diazo pyrazoleamides with silyl enol ethers was realized by employing a chiral N,N’-dioxide-Ni(II) complex catalyst. The process includes the formation of chiral nickel carbenoid intermediate and the following enantioselective cycloaddition reaction. The desired dihydrofuran O,O-acetal derivatives were obtained in good yields(up to 90%) with high enantioselectivity(up to 99% ee) under mild reaction conditions within short reaction time. On the basis of the determination of the catalyst structure, a possible transition state mode was proposed.Wei Yang Zhendong Yang Long Chen Yican Lu Cefei Zhang Zhishan Su Xiaohua Liu Xiaoming Feng 2023Chinese Chemical Letters2023,34,4:0
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