Primary Amine-Thioureas with Improved Catalytic Properties for “Difficult” Michael Reactions: Efficient Organocatalytic Syntheses of (S)-Baclofen, (R)-Baclofen and (S)-Phenibut
作者:Michail Tsakos、Christoforos G. Kokotos、George Kokotos
DOI:10.1002/adsc.201100636
日期:2012.3
Among the class of primary amine‐thioureas based on tert‐butyl esters of α‐amino acids, the most efficient organocatalyst for “difficult” Michaelreactions was identified. The derivative based on (S)‐di‐tert‐butyl aspartate and (1R,2R)‐diphenylethylenediamine provided the products of the reaction between aryl methyl ketones and nitroolefins in excellent yields and enantioselectivities. In addition
substrates in asymmetric epoxidation reactions. In this study, chiral primary amines are shown to catalyze the asymmetric epoxidation of α-substitutedacroleins, a versatile type of 1,1-disubstituted terminal alkene. Among various chiral primary amines explored, the chiral primary-tertiary vicinal diamine derived from trans-1,2-diphenylethane-1,2-diamine is identified as the optimal catalyst, which, in combination
Chiral Discrimination by a Binuclear Pd Complex Sensor Using <sup>31</sup>P{<sup>1</sup>H} NMR
作者:Zhongxiang Chen、Mingxue Yang、Zhaofeng Sun、Xuebo Zhang、Jing Xu、Guangling Bian、Ling Song
DOI:10.1021/acs.analchem.9b03661
日期:2019.11.19
An axially chiral binuclear μ-hydroxo Pd complex (BPHP) first served as an excellent chiral sensor for discriminating a variety of analytes including amino alcohol, amino amide, amino acid, mandelicacid, diol, diamine, and monoamine by 31P1H} NMR. A detailed recognition mechanism was proposed based on the single crystal and mass spectrum of Pd-complexes. In general, BPHP sensor, through extracting
轴向手性双核μ-羟基Pd络合物(BPHP)首先是出色的手性传感器,可通过31 P 1 H来区分各种分析物,包括氨基醇,氨基酰胺,氨基酸,扁桃酸,二醇,二胺和单胺NMR。基于单晶和钯络合物的质谱,提出了一种详细的识别机理。通常,BPHP传感器通过其Pd-OH基团提取分析物的酸性氢,与分析物的两个对映异构体形成稳定的非对映异构体复合物,从而为手性鉴别提供了可分辨的31 P 1 H} NMR分离信号。
Enantioselective construction of quaternary carbon centre catalysed by bifunctional organocatalyst
The bifunctional thiourea–tertiary amine derivatives of simple chiral diamines serve as highly enantioselective catalysts for the Michael addition of α-substituted cyanoacetates to vinyl sulfones, giving an efficient protocol for the construction of an all-carbon substituted quaternary stereocentre.
regio- and diastereoselectivity and enantioselectivity under ambient temperature. Significantly, the reactions accommodate the synthetically important but challenging substrates, such as linear aliphaticketones, with high regioselectivity and unprecedented syn diastereoselectivity. These results are in sharp contrast with the secondary amine mediated similar reactions wherein anti diastereoselectivity