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

2016 ◽  
Vol 40 (9) ◽  
pp. 7856-7865 ◽  
Author(s):  
Zsolt Rapi ◽  
Alajos Grün ◽  
György Keglevich ◽  
András Stirling ◽  
Péter Bakó
Keyword(s):  
Liquid Phase ◽  
Crown Ethers ◽  
Phase Transfer ◽  
Azacrown Ethers ◽  
Michael Reactions ◽  
Solid Liquid ◽  
Enantioselective Catalysts

Crown ethers derived from d-galactose generated good to excellent enantioselectivities in a few Michael reactions under solid–liquid phase transfer conditions.

scholarly journals Synthesis of Methyl 4,6-Di-O-ethyl-α-d-glucopyranoside-Based Azacrown Ethers and Their Effects in Asymmetric Reactions

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4668
Author(s):  
István Orbán ◽  
Bertalan Varga ◽  
Péter Bagi ◽  
László Hegedűs ◽  
Péter Bakó ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Liquid Phase ◽  
Crown Ethers ◽  
Asymmetric Induction ◽  
Crown Compounds ◽  
Two Phase ◽  
Azacrown Ethers ◽  
Negative Effect ◽  
Darzens Condensation ◽  
Solid Liquid

Carbohydrate-based crown ethers have been reported to be able to generate asymmetric induction in certain reactions. Previously, it was proved that the monosaccharide unit, the anomeric substituent, and the sidearm could influence the catalytic activity of the monoaza-15-crown-5 macrocycles derived from sugars. In order to gain information about the effect of the flexibility, 4,6-di-O-ethyl-glucoside-based crown compounds were synthesized, and their efficiency was compared to the 4,6-O-benzylidene analogues. It was found that the absence of the two-ring annulation has a negative effect on the enantioselectivity in liquid-liquid two-phase reactions: in the Darzens condensation of 2-chloroacetophenone and in the epoxidation of chalcone. The same trend was observed in the solid-liquid phase Michael addition of diethyl acetamidomalonate. Surprisingly, in the solid-liquid phase cyclopropanation of benzylidenemalononitrile, one of the new catalysts was highly enantioselective (99% ee).

A Selective Synthesis of Unsymmetrical 1,1'-Methylenebisdiazoles by Solid-liquid Phase Transfer Catalysis

Heterocycles ◽  
1986 ◽  
Vol 24 (8) ◽  
pp. 2233 ◽  
Author(s):  
Jos� Elguero ◽  
Sebastian Juli� ◽  
Carlos Mart地ez-Martorell
Keyword(s):  
Liquid Phase ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Selective Synthesis ◽  
Solid Liquid
Sign in / Sign up

Export Citation Format

Share Document