Direct Asymmetric Aldol Reaction Catalyzed by C2-Symmetrical Chiral Primary Amine Organocatalysts
作者:Gong-Jian Zhu、Chao-Shan Da、Ya-Ning Jia、Xiao Ma、Lei Yi
DOI:10.2174/157017810790533904
日期:2010.1.1
C-2-symmetrical chiral primaryamines were synthesized from chiral BINOL and diamines. Then their catalytic activities in the asymmetricaldolreactions were evaluated, and the result indicated that 1c was the optimal organocatalyst. The reaction of a variety of aromatic aldehydes with aliphatic ketones, catalyzed by 20 mol % 1c in the addition of benzoic acid in carbon tetrachloride, afforded the aldol products
2,4-Dinitrophenol as an Effective Cocatalyst: Greatly Improving the Activities and Enantioselectivities of Primary Amine Organocatalysts for Asymmetric Aldol Reactions
Seven primary amine organocatalysts 1a−g were readily prepared from natural primary amino acids via two steps and then were used to catalyze the directasymmetricaldolreaction, but they showed very poor enantioselectivities and activities. As an effective cocatalyst, 2,4-dinitrophenol (DNP) dramatically elevated the activities and enantioselectivities of these very inefficient primary amine organocatalysts
Unexpected Beneficial Effect of ortho-Substituents on the (S)-Proline-Catalyzed Asymmetric Aldol Reaction of Acetone with Aromatic Aldehydes
作者:Benjamin List、Alberto Martínez、Manuel van Gemmeren
DOI:10.1055/s-0033-1340920
日期:——
An intriguing effect of electronegative 2,6-substituents on the stereochemical outcome of (S) -proline-catalyzed aldol reactions between benzaldehyde derivatives and acetone is reported. Remarkably high enantioselectivities can be achieved with such substrates.
Highly efficient primary amine organocatalysts for the direct asymmetric aldol reaction in brine
作者:Xiao Ma、Chao-Shan Da、Lei Yi、Ya-Ning Jia、Qi-Peng Guo、Li-Ping Che、Feng-Chun Wu、Jun-Rui Wang、Wei-Ping Li
DOI:10.1016/j.tetasy.2009.05.032
日期:2009.7
amine organocatalysts, derivedfrom 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 directaldolreaction with a broad range of ketones and aromatic aldehydes, giving the corresponding aldol products
5-(Pyrrolidine-2-yl)tetrazole: Rationale for the Increased Reactivity of the Tetrazole Analogue of Proline in Organocatalyzed Aldol Reactions
作者:Antti Hartikka、Per I. Arvidsson
DOI:10.1002/ejoc.200500470
日期:2005.10
L-proline (2) in various organocatalyzed reactions. In the organocatalyzed direct asymmetric aldol reaction, acetone was reacted with aromatic and aliphaticaldehydes to afford the resulting β-hydroxy ketones in good yields and moderate to high enantiomeric excesses. The increased reactivity of 1, as compared to 2, has been rationalized through a combined computational and NMR spectroscopicstudy. It was