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Synthesis of Cinchona Alkaloid Sulfonamide Polymers as Enantioselective Catalysts for the Michael Addition Reaction of β‐Ketoester and Nitrostyrene
Author(s) -
Endo Yuta,
Takata Shohei,
Kumpuga Bahati Thom,
Itsuno Shinichi
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201702010
Subject(s) - cinchona , cinchonidine , sulfonamide , enantioselective synthesis , chemistry , bifunctional , catalysis , michael reaction , organic chemistry , moiety , cinchonine , polymerization , enantiomer , stereoselectivity , enantiomeric excess , cinchona alkaloids , combinatorial chemistry , polymer
Abstract Mizoroki–Heck (MH) polymerization of cinchonidine‐based sulfonamide dimers produces polymers containing a chiral sulfonamide moiety in each repeat unit. Quinidine sulfonamides are known to have excellent catalytic activity in the asymmetric Michael addition reaction of β‐ketoester and nitrostyrene. We found that cinchonidine sulfonamides used as bifunctional chiral catalysts showed even higher stereoselectivity in the same reaction. The polymers synthesized by MH polymerization also showed high levels of diastereo‐ and enantioselectivity (up to 99% enantiomeric excess) in the reaction. Owing to the insolubility of the polymeric catalysts, they were separated easily from the reaction mixture and reused several times without any loss of catalytic activity.