Synthesis of l-threitol-based crown ethers and their application as enantioselective phase transfer catalyst in Michael additions

Zsolt Rapi, Tamás Nemcsok, Ádám Pálvölgyi, György Keglevich, Alajos Grün, Péter Bakó

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9 Citations (Scopus)

Abstract

A few new l-threitol-based lariat ethers incorporating a monoaza-15-crown-5 unit were synthesized starting from diethyl l-tartrate. These macrocycles were used as phase transfer catalysts in asymmetric Michael addition reactions under mild conditions to afford the adducts in a few cases in good to excellent enantioselectivities. The addition of 2-nitropropane to trans-chalcone, and the reaction of diethyl acetamidomalonate with β-nitrostyrene resulted in the chiral Michael adducts in good enantioselectivities (90% and 95%, respectively). The substituents of chalcone had a significant impact on the yield and enantioselectivity in the reaction of diethyl acetoxymalonate. The highest enantiomeric excess (ee) values (99% ee) were measured in the case of 4-chloro- and 4-methoxychalcone. The phase transfer catalyzed cyclopropanation reaction of chalcone and benzylidene-malononitriles using diethyl bromomalonate as the nucleophile (MIRC reaction) was also developed. The corresponding chiral cyclopropane diesters were obtained in moderate to good (up to 99%) enantioselectivities in the presence of the threitol-based crown ethers.

Original languageEnglish
Pages (from-to)257-272
Number of pages16
JournalChirality
Volume29
Issue number6
DOIs
Publication statusPublished - Jan 1 2017

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Keywords

  • asymmetric Michael reactions
  • cyclopropanation
  • enantioselectivity
  • phase transfer catalysis
  • sugar-based crown ethers

ASJC Scopus subject areas

  • Analytical Chemistry
  • Catalysis
  • Pharmacology
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

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