Substrate selective catalytic molecular hydrogels: the role of the hydrophobic effect
作者:Cristina Berdugo、Juan F. Miravet、Beatriu Escuder
DOI:10.1039/c3cc45623d
日期:——
A catalytic hydrogel is reported for the substrate selective direct aldol reaction of aliphatic ketones based on their hydrophobicity and on the emergence of catalytic activity only after self-assembly of the catalyst.
Recyclable chiral diamine–polyoxometalate (POM) acids catalyzed asymmetric direct aldol reaction of aromatic aldehydes with long-chain aliphatic ketones
作者:Qiang Gao、Sheng-Mei Lu、Yan Liu、Can Li
DOI:10.1016/j.tetlet.2011.05.053
日期:2011.7
In this Letter, we studied the asymmetric direct aldol reaction of long-chain aliphatic ketones with aromatic aldehydes, using chiral diamine–polyoxometalate acid combined organocatalysts. High yields (up to 90%) and enantioselectivities (up to 90% ee) were obtained under solvent-free conditions with the optimized catalyst. Furthermore, such organocatalysts could be easily recycled and reused for four
Organo-catalyzed highly diastereo- and enantio-selective direct aldol reactions in water
作者:Jun-Feng Zhao、Long He、Jun Jiang、Zhuo Tang、Lin-Feng Cun、Liu-Zhu Gong
DOI:10.1016/j.tetlet.2008.03.131
日期:2008.5
The asymmetric directaldolreactions of a wide scope of aromatic aldehydes, with unmodified ketones in the presence of 1 mol % of organocatalyst prepared from (2R,3R)-diethyl 2-amino-3-hydroxysuccinate and trans-4-hydroxy-l-proline, were performed in water, affording aldol products in high yields with excellent diastereoselectivities of up to >99:1 and enantioselectivities of up to 98%.
A combination of zinc triflate and chiral C2-symmetrical prolinamide ligand leads to high enantioselectivities in direct aldol reactions essentially assisted by water. The presence of 5 mol % of the catalyst affords an asymmetric intermolecular aldol reaction between unmodified ketones and aldehydes to give anti-products with excellent enantioselectivities ranging from 86–98 % ee. The same bis(prolinamide)
A new (S)-prolinamide modified by an ionic liquid moiety—a high performance recoverable catalyst for asymmetric aldol reactions in aqueous media
作者:Dmitry E. Siyutkin、Alexander S. Kucherenko、Sergei G. Zlotin
DOI:10.1016/j.tet.2009.11.033
日期:2010.1
New prolinamide derivatives modified with ionicliquid moieties were synthesized and studied as organocatalysts in asymmetricaldolreactions in water. Aldolreactions between cycloalkanones or methylketones and aromatic aldehydes proceeded under studied conditions with high conversions (yields), diastereo- and enantioselectivities in the presence of a hydrophobic catalyst bearing a PF6 anion (1–5 mol %)