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Thiourea‐Catalyzed Asymmetric Michael Addition of Carbazolones to 2‐Chloroacrylonitrile: Total Synthesis of 5,22‐Dioxokopsane, Kopsinidine C, and Demethoxycarbonylkopsin
Author(s) -
Ni Dongshun,
Wei Yi,
Ma Dawei
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201805905
Subject(s) - thiourea , michael reaction , total synthesis , catalysis , chemistry , combinatorial chemistry , ring (chemistry) , enantioselective synthesis , oxidative coupling of methane , stereochemistry , organic chemistry
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 Mn III ‐mediated oxidative cyclization to create the caged ring system and a SmI 2 ‐mediated reductive coupling as key steps.