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
Highly enantioselective aldol reactions using a tropos dibenz[c,e]azepine organocatalyst
作者:Barry Lygo、Christopher Davison、Timothy Evans、James A.R. Gilks、John Leonard、Claude-Eric Roy
DOI:10.1016/j.tet.2011.09.101
日期:2011.12
The four-step synthesis of a chiral primary tertiary diamine salt, possessing a tropos dibenz[c,e]azepine ring is described. It is shown that 3.5–5 mol % of this salt is capable of promoting highly enantioselective crossed-aldol reactions between cyclohexanone and a series of aromatic aldehydes. In all cases, the aldol reactions proceed with high diastereoselectivity for the anti-aldol product. The
An efficient asymmetric organocatalyst was developed for the direct aldol reaction between ketones and aldehydes to afford β-hydroxy ketones in high stereoselectivity (anti/syn up to 92:8, ee up to >99%). The key of the success was the use of activated molecular sieves (4 ŠMS), which acted as a water scavenger. The influence of additives such as water or different types of molecular sieves on the reactivity and stereoselectivity of the reaction was also studied.
一种高效的非对称有机催化剂被开发出来,用于酮和醛之间的直接aldol反应,以高立体选择性(anti/syn高达92:8,ee高达>99%)制备β-羟基酮。成功的关键在于使用了活化的分子筛(4 Å MS),其作为水的清除剂。还研究了水分或不同类型分子筛等添加剂对反应活性和立体选择性的影响。
Asymmetric Aldol Reaction Catalyzed by the Anion of an Ionic Liquid
作者:Vincent Gauchot、Andreea R. Schmitzer
DOI:10.1021/jo300737u
日期:2012.6.1
its applications as a catalyst for the asymmetric aldolreaction. By performing the aldolreaction in [Bmim]NTf2 as a solvent, we report excellent isolated yields of the aldol product (up to 99%), as well as modest to excellent selectivities (dr superior to 99:1. ee up to 89%). Mechanistic insights and the origins of the selectivity of the aldolreaction are discussed on the basis of the results obtained
Design and preparation of a novel prolinamide-based organocatalyst for the solvent-free asymmetric aldol reaction
作者:Rafaela de S. Martins、Mathias P. Pereira、Pedro P. de Castro、Fernanda I. Bombonato
DOI:10.1016/j.tet.2019.130855
日期:2020.1
proline-derived catalyst, providing access to the desired adducts in up to 95% yield, 1:19 syn/anti and 98% e.e. Moreover, even sterically bulky aldehydes and substituted cyclohexanones were well tolerated. DFT calculations and control experiments indicated that several hydrogen bonding interactions between the aldehyde and the enamine intermediate are responsible for the stereoselective chiral induction process