Towards a Series of Chiral Primary Amines Bearing α-Amino Acid and Benzo[d]imidazole Pendants, and Their Application in Asymmetric Aldol Reactions
作者:Filip Bureš、Pravinkumar Mohite、Pavel Drabina
DOI:10.1055/s-0036-1588107
日期:——
path towards chiral primary amines bearing α-amino acid and benzo[d]imidazole pendants has been developed. Six starting essential α-amino acids were converted into the target chiral amines in a four-step synthesis. The prepared amines were screened as organocatalysts in the direct asymmetric aldol reaction between 4-nitrobenzaldehyde or isatin and acetone or cyclohexanone. The aldoladducts were obtained
摘要 已经开发出一种简单的反应路线,该路线指向带有α-氨基酸和苯并[ d ]咪唑侧基的手性伯胺。在四个步骤的合成中,将六个起始必需α-氨基酸转化为目标手性胺。在4-硝基苯甲醛或靛红与丙酮或环己酮之间的直接不对称醛醇缩合反应中,将制备的胺筛选为有机催化剂。以良好的化学收率,高达97:3的非对映选择性(与环己酮的反应)和高达71%ee的对映选择性获得醛醇加合物。三氟乙酸和苯甲酸被证明是分别在4-硝基苯甲醛和靛红上进行羟醛合成的最佳助催化剂。 已经开发出一种简单的反应路线,该路线指向带有α-氨基酸和苯并[ d ]咪唑侧基的手性伯胺。在四个步骤的合成中,将六个起始必需α-氨基酸转化为目标手性胺。在4-硝基苯甲醛或靛红与丙酮或环己酮之间的直接不对称醛醇缩合反应中,将制备的胺筛选为有机催化剂。以良好的化学收率,高达97:3的非对映选择性(与环己酮的反应)和高达71%ee的对映选择性获得醛醇加合物。三氟
Electrostatic Repulsion and Hydrogen-Bonding Interactions in a Simple<i>N</i>-Aryl-<scp>L</scp>-valinamide Organocatalyst Control the Stereoselectivity in Asymmetric Aldol Reactions
作者:Yuya Tanimura、Kenji Yasunaga、Kaori Ishimaru
DOI:10.1002/ejoc.201301138
日期:2013.10
A novel stereocontrol method for asymmetric aldol reactions of aldehydes with ketones is described. The stereoselectivity of the products is controlled by the electrostaticrepulsion and hydrogen-bonding interactions of an N-aryl-L-valinamide catalyst. The use of this catalyst in a cross-aldol reaction allows easy access to bioactive 3-cyclohexanone-3-hydroxy-2-oxindole with excellent diastereo- (syn/anti
In this work, six novelaxiallyunfixed biaryl‐based water‐compatible bifunctionalorganocatalysts were designed and synthesized for the organocatalytic access to a variety of 3‐alkyl‐3‐hydroxy‐2‐oxindole derivatives via aldol reactions in water. Organocatalyzed by 5a, the direct aldol reactions of isatins with enolisable ketones underwent readily in water, furnishing the structurally diverse 3‐al
The synthesis and application of a newly designed C2-symmetric chiral bifunctional triamine family (C2-CBT) is reported. These enantiopure chiral triamine scaffolds can be accessed in multigram amounts from simple amino acids while avoiding chromatographic purification. As a proof of principle, C2-CBT has been studied in the aldol reaction of cyclic ketones with isatins, with the target tertiary alcohols
Primary amine catalyzed aldol reaction of isatins and acetaldehyde
作者:Qunsheng Guo、John Cong-Gui Zhao
DOI:10.1016/j.tetlet.2012.01.108
日期:2012.4
alkaloid-derived chiral primary amines were applied as the catalyst for the cross aldol reaction of isatins with acetaldehyde. With the quinine-derived amine catalyst 3, the desired aldol products were obtained in high yields and good enantioselectivities (up to 93% ee) under the optimized conditions. Although other enolizable aldehydes and ketones may also be applied in this reaction, the ee values obtained