Synthesis of Cinchona Alkaloid Sulfonamide Polymers as Enantioselective Catalysts for the Michael Addition Reaction of β‐Ketoester and Nitrostyrene. Issue 31 (2nd November 2017)

• Record Type: Journal Article
• Authors: Endo, Yuta; Takata, Shohei; Kumpuga, Bahati Thom; Itsuno, Shinichi
• Is Part Of: ChemistrySelect. Volume 2:Issue 31(2017)
• Page Start: 10107
• Page End: 10111
• Publication Date: 2017-11-02
• Subjects: cinchona alkaloid -- Michael addition -- organocatalysis -- polymer catalyst -- sulfonamide; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201702010
• Languages: English
• ISSNs: 2365-6549

Abstract

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. Abstract : Polymer catalyst: cinchonidine‐derived sulfonamides were polymerized by Mizoroki‐Heck polymerization. Chiral polymers showed excellent catalytic activity with high levels of stereoselectivity (dr> 10, 99% ee) in the Michael reaction of β‐ketoester and nitrostyrene. The polymer catalysts were easily recovered from the reaction mixture and reused.