Enantioselectivity switch controlled by N,N′-di- or N,N,N′,N′-tetra-substituted chiral thiophosphorodiamide ligands, structural relatives of thioureas, in catalytic additions of diethylzinc to aldehydes
摘要:
We have developed a series of new chiral thiophosphorodiamide ligands derived from (1R,2R)-(+)-1,2-diphenylethylenediamine, which are the structural relatives of thioureas. An investigation into their catalytic properties in asymmetric additions of diethylzinc to aldehydes has shown that N,N,N',N'-tetra-substituted chiral thiophosphorodiamides can give (R)-secondary alcohols with up to 98% yield and 98% ee, while N,N'-di-substituted chiral thiophosphorodiamides give (S)-secondary alcohols with up to 99% yield and 97% ee values. The enantioselectivity switch is highly efficient with a broad substrate scope. We have also proposed hypothetical reaction pathways, which result in an enantioselectivity switch. (C) 2013 Elsevier Ltd. All rights reserved.
Frustrated Lewis Acid/Brønsted Base Catalysts for Direct Enantioselective α-Amination of Carbonyl Compounds
作者:Ming Shang、Xiaoxu Wang、Seung Moh Koo、Jennifer Youn、Jessica Z. Chan、Wenzhi Yao、Brian T. Hastings、Masayuki Wasa
DOI:10.1021/jacs.6b11908
日期:2017.1.11
A method for enantioselective direct α-amination reactioncatalyzed by a sterically "frustrated" Lewisacid/Brønsted base complex is disclosed. Cooperative functioning of the Lewisacid and Brønsted base components gives rise to in situ enolate generation from monocarbonyl compounds. Subsequent reaction with hydrogen-bond activated dialkyl azodicarboxylates delivers α-aminocarbonyl compounds in high
作者:Si Joon Park、In-Soo Hwang、Young Jun Chang、Choong Eui Song
DOI:10.1021/jacs.0c11815
日期:2021.2.17
hemithioacetals which proceeds viaenantioselective protonation of an ene-diol intermediate. The use of on-water condition turns on this otherwise extremely unreactive catalytic reaction as a result of the strengthened hydrogen bonds of water molecules near the hydrophobic reaction mixture. Furthermore, under on-water conditions, especially under biphasic microfluidic on-water conditions, access of bulk water into
水中前手性碳负离子的催化对映选择性质子化是生物系统中的一种常见转化,但由于质子在水中异常快速的运动会导致不受控制的外消旋质子化,因此这超出了合成化学家的能力。在这里,我们展示了水的关键作用,它能够通过烯二醇中间体的对映选择性质子化进行半硫缩醛的高度对映选择性乙二醛酶 I 模拟催化异构化。由于疏水反应混合物附近的水分子的氢键增强,因此水上条件的使用开启了这种原本极其不活泼的催化反应。此外,在水上条件下,特别是在双相微流体水上条件下,