water-compatible proline catalysts (4–6) derived from calixarene bearing a hydrophobic nature have been synthesised. It was found that the compound 4 was a highly efficient organocatalyst for aldol reactions occurred in the water. Under optimised reaction conditions, high yields (up to 82%), good enantioselectivities (ee up to 81%) and high diastereoselectivities (dr up to 91:9) were obtained.
Prolinamides of Aminouracils, Organocatalyst Modifiable by Complementary Modules
作者:Karen M. Ruíz-Pérez、Beatriz Quiroz-García、Marcos Hernández-Rodríguez
DOI:10.1002/ejoc.201800886
日期:2018.11.8
Prolinamide organocatalysts with aminouracils have the features of enhanced NH acidity, an additional hydrogen‐bond donor and the self‐assembly with complementary modules by Watson–Crick pairing. Each module affects the selectivity of the reaction and particularly 2,6‐diaminopyridine is beneficial to the selectivity in the reaction.
[reaction: see text] Readily tunable and bifunctional L-prolinamides as novel organocatalysts have been developed, and their catalytic activities were evaluated in the direct asymmetric Aldolreactions of various aromatic aldehydes and cyclohexanone. High isolated yields (up to 94%), enantioselectivities (up to 99% ee), and anti-diastereoselectivities (up to 99:1) were obtained under the optimal conditions
Unprecedented bifunctional enamine–metal Lewisacidcatalysts have been developed. In this bifunctional catalytic system, a tridentateligand tethered with a chiral secondary amine was designed to solve the acid–base self-quenching problem leading to catalyst inactivation. This new bifunctional enamine–metal Lewisacidcatalyst was found to catalyze aldol reactions of ketones efficiently in high yields
<i>N</i>-Primary-Amine-Terminal β-Turn Tetrapeptides as Organocatalysts for Highly Enantioselective Aldol Reaction
作者:Feng-Chun Wu、Chao-Shan Da、Zhi-Xue Du、Qi-Peng Guo、Wei-Ping Li、Lei Yi、Ya-Ning Jia、Xiao Ma
DOI:10.1021/jo9005766
日期:2009.7.3
solution. They were first applied to catalyze aldolreactions, and were found to be effective catalysts for the transformations. The tetrapeptide Val-d-Pro-Gly-Leu-OH (1g) was the optimal organocatalyst. It was shown that the intensive β-turn conformation, indicated by CD and NOESY spectra, contributed to the (R)-aldol and high enantioselectivity of the reaction of acetone in MeOH, whereas the sharply varied
设计并合成了四肽,该四肽包含一个终止的伯胺和构象受限的d -Pro-Gly或d -Pro-Aib(2-氨基异丁酸)链段作为强β-转核元素,并通过N-模块二肽与溶液中的C模块二肽。它们首先被用于催化羟醛反应,并被发现是有效的转化催化剂。四肽Val- d -Pro-Gly-Leu-OH(1g)是最佳的有机催化剂。结果表明,在密集的β转角构象,通过CD和NOESY光谱表明,促成了(ř)-丙酮中的丙酮反应具有较高的对映选择性,而急剧变化的构象应有助于1,2-二氯乙烷(DCE)中反应的低对映选择性和(S)产物。羟基丙酮反应中的不对称诱导不受溶剂的影响,在MeCN中添加1克添加剂(S)-BINOL可达到主要的反产物。