Synthesis of chiral crown ethers derived from D-galactose and their application in enantioselective reactions

Zsolt Rapi, Tamás Nemcsok, Péter Bagi, G. Keglevich, P. Bakó

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3 Citations (Scopus)

Abstract

A few new α- and β-D-galactopyranoside-based chiral lariat ethers of monoaza-15-crown-5 type were synthesized. These macrocycles proved to be efficient catalysts in a few asymmetric reactions under mild phase transfer conditions. The catalytic effect of the lariat ethers with methoxy, ethoxy, isopropoxy and aryloxy substituents on the C-1 of the sugar unit in both α and β positions was compared. In the presence of β-D-galactopyranoside-based crown ethers, the asymmetric Darzens condensation of α-chloroacetophenone and benzaldehyde, the epoxidation of trans-chalcone, the cyclopropanation (MIRC reaction) of benzylidenemalononitrile and 2-benzylidene-1,3-indandione with diethyl bromomalonate were performed with enantioselectivities of 61%, 64%, 86% and 96%, respectively. In all reactions, the β-anomers were more efficient in terms of enantioselectivity than the α forms.

Original languageEnglish
Pages (from-to)3993-4004
Number of pages12
JournalTetrahedron
Volume75
Issue number30
DOIs
Publication statusPublished - Jul 26 2019

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Keywords

  • Chiral crown ethers
  • Enantioselectivity
  • Phase transfer catalysis

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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