Synthesis of α-d-galactose-based azacrown ethers and their application as enantioselective catalysts in Michael reactions

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15 Citations (Scopus)

Abstract

New chiral monoaza-15-crown-5 type macrocycles annelated to methyl 4,6-O-benzylidene-α-d-galactopyranoside have been synthesized. These crown ethers proved to be efficient catalysts in a few asymmetric reactions under mild phase transfer catalytic conditions. Michael adducts were formed with good to excellent enantioselectivities, so the addition of diethyl acetamidomalonate to β-nitrostyrene took place with up to 92% ee, while the reaction of diethyl acetoxymalonate with chalcones proceeded with up to 99% ee. Using diethyl bromomalonate as the nucleophile, the chiral cyclopropane derivatives were formed in up to 99% ee with the addition to chalcone, in up to 78% ee in the reaction with benzylidene malononitrile, and in up to 76% ee in the reaction with 2-benzylidene-1,3-diphenyl-1,3-propanedione applying α-d-galactoside-based crown ethers as the catalysts. In the Michael addition, the substituents of the chalcone had a considerable impact on the outcome of the reactions. Quantum chemical calculations have also been employed to evaluate the origin of the stereoselectivities.

Original languageEnglish
Pages (from-to)7856-7865
Number of pages10
JournalNew Journal of Chemistry
Volume40
Issue number9
DOIs
Publication statusPublished - jan. 1 2016

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

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