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

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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 - 2016

Fingerprint

Crown Ethers
Chalcone
Crown ethers
Ethers
Galactose
Chalcones
Galactosides
Stereoselectivity
Nucleophiles
Catalysts
Enantioselectivity
Derivatives
dicyanmethane
15-crown-5
cyclopropane
dibenzoylmethane

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

Cite this

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title = "Synthesis of α-d-galactose-based azacrown ethers and their application as enantioselective catalysts in Michael reactions",
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.",
author = "Zsolt Rapi and A. Gr{\"u}n and G. Keglevich and A. Stirling and P. Bak{\'o}",
year = "2016",
doi = "10.1039/c6nj02030e",
language = "English",
volume = "40",
pages = "7856--7865",
journal = "New Journal of Chemistry",
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T1 - Synthesis of α-d-galactose-based azacrown ethers and their application as enantioselective catalysts in Michael reactions

AU - Rapi, Zsolt

AU - Grün, A.

AU - Keglevich, G.

AU - Stirling, A.

AU - Bakó, P.

PY - 2016

Y1 - 2016

N2 - 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.

AB - 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.

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