A series of functionalized ionicliquids (FILs) incorporated with chiral-pyrrolidine unit have been synthesized and tested as reusable organocatalysts for direct aldolreactions. FIL 1b in combination with acetic acid and water as additives could effectively catalyze direct aldolreactions of various ketone donors in high yields and the FIL catalyst was easily recycled and reused for six times with
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
The application of a structurally simple, recyclable, and large-scale l-prolinamide catalyst for asymmetric aldol reactions
作者:Zhi Guan、Yuan Luo、Bao-Qiang Zhang、Krystal Heinen、Da-Cheng Yang、Yan-Hong He
DOI:10.1016/j.tetasy.2014.04.009
日期:2014.5
With heterocyclic ketones or cyclohexanone, the aldolreactions gave products in high yields and with respectable enantioselectivities (87–99% ee) and diastereoselectivities (up to >99:1 anti/syn). The catalyst could be recycled and reused up to seven times resulting in good yields and with good selectivities. This catalyst is also efficient in large-scale reactions with the enantioselectivities remaining
Direct asymmetric aldol reactions between aldehydes and ketones catalyzed by l-tryptophan in the presence of water
作者:Zhaoqin Jiang、Hui Yang、Xiao Han、Jie Luo、Ming Wah Wong、Yixin Lu
DOI:10.1039/b921460g
日期:——
Primary amino acids and their derivatives were investigated as catalysts for the direct asymmetric aldol reactionsbetween ketones and aldehydes in the presence of water, and L-tryptophan was shown to be the best catalyst. Solvent effects, substrate scope and the influence of water on the reactions were investigated. Quantum chemical calculations were performed to understand the origin of the observed
Synthesis of new ionic-liquid-tagged organocatalysts and their application in stereoselective direct aldol reactions
作者:Sadaf S. Khan、Jabbar Shah、Jürgen Liebscher
DOI:10.1016/j.tet.2010.04.115
日期:2010.7
and subsequent N-methylation. These products were applied as ionic-liquid-tagged organocatalysts in asymmetric direct aldolreactions. Remarkably, a lysine-derived conjugate performed better than proline derivatives. Evidence was found that IL-tagging improved the catalytic performance. Recycling of the organocatalyst was easily possible by extraction of products.