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Enantioselective Michael/aza‐Michael/Cyclization Organocascade to Tetracyclic Spiroindolines: Concise Total Synthesis of Kopsinine and Aspidofractine
Author(s) -
Wu Xiaoyu,
Huang Jianbiao,
Guo Beibei,
Zhao Long,
Liu Yong,
Chen Jie,
Cao Weiguo
Publication year - 2014
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201400363
Subject(s) - enantioselective synthesis , michael reaction , chemistry , moiety , acrolein , propargyl , nucleophile , aldehyde , total synthesis , stereochemistry , organocatalysis , organic chemistry , combinatorial chemistry , catalysis
Abstract Kopsinine and related alkaloids are attractive synthetic targets because of their structural complexity and biological activities. An organocatalytic Michael addition/aza‐Michael addition/cyclization cascade sequence has been developed for the enantioselective preparation of tetracyclic spiroindolines from 2,3‐disubstituted indoles and propargyl aldehyde in moderate to good yields and good to excellent enantioselectivities. The synthetic value of these advanced structures has been demonstrated by the synthesis of kopsinine and related alkaloids. Key steps for the concise synthesis of these alkaloids included an efficient enantioselective construction of tetracyclic spiroindolines bearing a dienamino ester moiety and the organocatalyzed nucleophilic addition of a dienamino ester to acrolein.