Ruthenium catalyzed asymmetric hydrogenation of α- and β-keto esters in ionic liquids using chiral P-Phos ligand

2005 ◽  
Vol 83 (6-7) ◽  
pp. 903-908 ◽  
Author(s):  
Kim Hung Lam ◽  
Lijin Xu ◽  
Lichun Feng ◽  
Jiwu Ruan ◽  
Qinghua Fan ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Room Temperature ◽  
Asymmetric Hydrogenation ◽  
Room Temperature Ionic Liquids ◽  
Keto Ester ◽  
Keto Esters ◽  
Simple Extraction

Chiral dipyridylphosphine ligand P-Phos was used in the Ru catalyzed asymmetric hydrogenation of α- and β-keto esters in room temperature ionic liquids (RTILs) with high conversions and good to excellent enantioselectivities. The catalyst was recycled by simple extraction and reused five times without loss of activity and enantioselectivity.Key words: ruthenium, asymmetric hydrogenation, keto ester, ionic liquids, P-Phos.

scholarly journals Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 355
Author(s):  
Fabricio R. Bisogno ◽  
Rosario Fernández ◽  
Jose María Lassaletta ◽  
Gonzalo de de Gonzalo
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Room Temperature ◽  
Catalyst Activity ◽  
Room Temperature Ionic Liquids ◽  
Tertiary Alcohols ◽  
Tert Butyl ◽  
Keto Esters ◽  
Enantioselective Addition ◽  
Positive Effect

Room temperature ionic liquids (RTILs) have been widely used as (co)solvents in several catalytic processes modifying, in most of the cases, the catalyst activity and/or the selectivity for the studied reactions. However, there are just a few examples of their use in hydrogen bonding organocatalysis. In this paper, we show the positive effect of a set of imidazole-based ionic liquids ([bmim]BF4 and [hmim]PF6) in the enantioselective addition of formaldehyde tert-butylhydrazone to prochiral α-keto esters catalyzed by a sugar-based chiral thiourea. Reactions performed in the presence of low percentages of RTILs led to an increase of the catalyst activity, thereby making possible to work at lower temperatures. Thus, the chiral tert-butyl azomethyl tertiary alcohols could be obtained with moderate to good conversions and higher enantioselectivities for most of the studied substrates when using up to 30 vol% of [hmim]PF6 as a cosolvent in processes performed in toluene.

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