Proline-Glycine Dipeptidic Derivatives of Chiral Phosphoramides as Organocatalysts for the Enantiodivergent Aldol Reaction of Aryl Aldehydes and Isatins with Cyclohexanone in the Presence of Water
(S)-proline-glycine dipeptides and incorporating a chiral phosphoramide fragment was accomplished. These chiral compounds catalyze the enantioselective aldol addition reaction of cyclohexanone to prochiral aryl aldehydes and isatins in the presence of water. These chiral organocatalysts represent some of the few proline-derived compounds capable to catalyze aldol-type addition of cyclohexanone to isatins, a C–C
Synthesis of a new chiral organocatalyst derived from (S)-proline containing a 1,2,4-triazolyl moiety and its application in the asymmetric aldol reaction. Importance of one molecule of water generated in situ
作者:Omar Sánchez-Antonio、Eusebio Juaristi
DOI:10.1016/j.tetlet.2019.151128
日期:2019.10
yield. Our triazolyl-containing heterocycle was evaluated as organocatalyst (10 mol% load, under neat reaction conditions) in the enantioselective aldolreaction between four different types of ketones and a variety of aryl aldehydes. Good results in terms of enantioselectivity and chemical yield were observed under solvent-free reaction conditions and in the absence of any additive. Evidence is provided
(2S,4R)-Hyp-(S)-Phe-OMe dipeptide supported on imidazolium tagged molecules as recoverable organocatalysts for asymmetric aldol reactions using water as reaction medium
作者:Arturo Obregón-Zúñiga、Eusebio Juaristi
DOI:10.1016/j.tet.2017.07.037
日期:2017.9
evaluated as organocatalysts in the asymmetric aldol reaction using water as solvent. It was found that catalysts incorporating the hexanoyl linker are active down to 5 mol% and afford aldol products with up to 94% yield, up to 98:2 dr and up to 97:3 er. This chiral imidazolium catalyst was reused up to 6 times without any loss in the stereoselectivity of asymmetric aldol reactions. By contrast, organocatalysts
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
Improving the Catalytic Performance of (<i>S</i>)-Proline as Organocatalyst in Asymmetric Aldol Reactions in the Presence of Solvate Ionic Liquids: Involvement of a Supramolecular Aggregate
For the first time, a highly efficient and stereoselective asymmetricaldolreaction employing (S)-proline in the presence of solvate ionicliquids is reported. The reaction seems to proceed via a supramolecular aggregate of (S)-proline, the solvate ionicliquid, and water, affording high yields and excellent stereoselectivities with low catalyst loadings.