Thiourea‐Catalyzed Asymmetric Michael Addition of Carbazolones to 2‐Chloroacrylonitrile: Total Synthesis of 5,22‐Dioxokopsane,Kopsinidine C,and Demethoxycarbonylkopsin |
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| Authors: | Dr Dongshun Ni Dr Yi Wei Prof?Dr Dawei Ma |
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| Institution: | State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China |
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| Abstract: | A modified Takemoto catalyst enabled the asymmetric Michael addition of carbazolones to 2‐chloroacrylonitrile to afford 3,3‐disubstituted carbazolones with excellent enantioselectivity. This method was successfully applied to total syntheses of three Kopsia alkaloids which featured an unprecedented MnIII‐mediated oxidative cyclization to create the caged ring system and a SmI2‐mediated reductive coupling as key steps. |
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| Keywords: | asymmetric catalysis indole alkaloids Michael addition organocatalysis total synthesis |
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