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Facile Synthesis of Chiral Spirooxindole‐Based Isotetronic Acids and 5‐1 H ‐Pyrrol‐2‐ones through Cascade Reactions with Bifunctional Organocatalysts
Author(s) -
Guo Wengang,
Wang Xu,
Zhang Boyu,
Shen Shuai,
Zhou Xin,
Wang Peng,
Liu Yan,
Li Can
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201402945
Subject(s) - bifunctional , cinchona , chemistry , isatin , catalysis , organocatalysis , cinchona alkaloids , enantioselective synthesis , organic chemistry , adduct , cascade reaction , combinatorial chemistry
Unprecedented organocatalyzed asymmetric cascade reactions have been developed for the facile synthesis of chiral spirooxindole‐based isotetronic acids and 5‐1 H ‐pyrrol‐2‐ones.The asymmetric 1,2‐addition reactions of α‐ketoesters to isatins and imines by using an acid–base bifunctional 6′‐OH cinchona alkaloid catalyst, followed by cyclization and enolization of the resulting adducts, gave chiral spiroisotetronic acids and 5‐1 H ‐pyrrol‐2‐ones, respectively, in excellent optical purities (up to 98 % ee ). FT‐IR analysis supported the existence of hydrogen‐bonding interaction between the 6′‐OH group of the cinchona catalyst and an isatin carbonyl group, an interaction that might be crucial for catalyst activity and stereocontrol.