1364122-01-9

Upstream product

• 459-57-4 4-fluorobenzaldehyde 
• 120-92-3 cyclopentanone 

Relevant academic research and scientific papers

(L)-Prolinamide imidazolium hexafluorophosphate ionic liquid as an efficient reusable organocatalyst for direct asymmetric aldol reaction in solvent-free condition

We have designed a new hydrophobic ionic liquid derived from bromoester of trans-4-hydroxy-(l)-prolinamide and N-methylimidazole. (l)-Prolinamide imidazolium hexafluorophosphate ionic liquid (2 mol%) found to be an excellent organocatalyst for direct asymmetric aldol reaction between 4-nitrobenzaldehyde and cyclohexanone using acetic acid (2 mol%) as an additive at -15 °C in solvent-free condition, the aldol product was afforded in excellent yield with diastereomeric ratio (anti/syn; 97:3) and 94% ee of anti-aldol product. Ionic liquids can catalyze the direct aldol reaction between benzaldehyde derivatives and cycloalkanones and the best dr (anti/syn; 99.9/0.01) and 99% ee was obtained for aldol product of 2-trifluoromethyl benzaldehyde and cyclohexanone. (l)-Prolinamide imidazolium hexafluorophosphate ionic liquid was reused up to 6 continuous cycles without decrease in the conversion of the product with 92% ee and found to be superior than its counterpart trans-4-hydroxy-(l)-prolinamide. Continuous cycle experiments do not require isolation of the catalyst after each cycle. The results of reusability of the ionic liquid catalyst were found to be better than most of other reported reusable catalysts.

Synergistic effects within a C2-symmetric organocatalyst: The potential formation of a chiral catalytic pocket

This study describes the synthesis of five novel C2-symmetric organocatalysts that facilitate the on-water asymmetric aldol reaction at low catalyst loading (1 mol%) without the use of additives. Each catalyst is composed of two diprolinamide units joined by a symmetric alkyl bridging group allowing for systematic modulation of catalytic site proximity. Typically, catalysts in this manuscript which bear the catalytic units in close proximity gave the best reaction outcomes in terms of conversion (up to >99%), diastereomeric ratio (4/96, syn/anti) and enantiomeric excess (up to 97%). This effect has been attributed to the assembly of a chiral pocket, facilitated by hydrogen bonding at the oil-in-water interface. The Royal Society of Chemistry 2013.

Direct asymmetric aldol reactions in water catalysed by a highly active C2-symmetrical bisprolinamide organocatalyst

A novel C2-symmetrical bisprolinamide organocatalyst was synthesised and used to facilitate asymmetric direct aldol reactions in a water emulsion. Reactions were performed at room temperature with very low catalyst loadings (1-2.5 mol%) without the required use of additives, co-catalysts or extended reaction times (24 h). This catalyst system was then used with a variety of aldehyde substrates showing good reaction generality for benzaldehydes with cyclohexanone (dr range 77/23 to 99/1, anti/syn; ee range 33% to 99%) and moderate scope with cyclopentanone (dr range 45/55 to 76/24, anti/syn; ee range 14% to 68%). Ultra-low catalysts loadings (0.1 and 0.05 mol%) were also investigated demonstrating catalyst turnover numbers in the order of 1000.

Highly efficient primary amine organocatalysts for the direct asymmetric aldol reaction in brine

Organocatalytic systems made up of six primary amine organocatalysts, derived from natural primary amino acids, in combination with 2,4-dinitrophenol (DNP) have proven to be efficient in the presence of brine without further addition of organic solvents. The system formed by 1f and DNP was the most efficient one; it can catalyze the direct aldol reaction with a broad range of ketones and aromatic aldehydes, giving the corresponding aldol products in high yields with up to nearly perfect diastereo- and enantioselectivities (up to 99/1 syn/anti, >99% ee).