Catalytic Asymmetric Cyano-Ethoxycarbonylation Reaction of Aldehydes Using a Novel <i>C</i><sub>2</sub>-Symmetric Chiral <i>N</i>,<i>N</i>′-Dioxide Titanium Complex
作者:Xiaoming Feng、Qinghan Li、Lu Chang、Xiaohua Liu
DOI:10.1055/s-2006-947322
日期:2006.7
The asymmetric addition of ethyl cyanoformate to a range of aldehydes was efficiently catalyzed by a easily prepared C 2 -symmetric chiral N,N'-dioxide-Ti(IV) complex in high yields with up to 90% ee under mild conditions. A linear effect between the enantiopurity of the ligand and the enantiopurity of the product was observed.
氰基甲酸乙酯与一系列醛的不对称加成被一种易于制备的 C 2 -对称手性 N,N'-二氧化钛-Ti(IV) 配合物有效催化,在温和条件下的收率高达 90%。观察到配体的对映纯度和产物的对映纯度之间存在线性效应。
Enantioselective phospha-Michael reaction of diethyl phosphonate with exocyclic α,β-unsaturated benzocyclic ketones catalyzed by a dinuclear zinc−AzePhenol catalyst
作者:Na Shao、Yong-Yang Luo、Hui-Jie Lu、Yuan-Zhao Hua、Min-Can Wang
DOI:10.1016/j.tet.2018.03.016
日期:2018.4
The dinuclear zinc complexes as high performance catalysts were used to catalyze phospha-Michael reaction of exocyclic α,β-unsaturated benzocyclic ketones under mild conditions, and the desired products possessing 1-indanones or 1-tetralones skeleton were obtained with excellent enantioselectivities of up to 99%/99% ee and yields of up to 99%. The absolute stereochemistry of the major products catalyzed
Electronic Effects of Ligand Substitution in a Family of Co<sup>II</sup><sub>2</sub> PARACEST pH Probes
作者:Agnes E. Thorarinsdottir、Scott M. Tatro、T. David Harris
DOI:10.1021/acs.inorgchem.8b01896
日期:2018.9.4
pH unit–1 at 37 °C. Here, we demonstrate through a series of CF3-functionalized CoII2 complexes [(XL′)Co2(etidronate)]− (X = NO2, F, Me), that modest changes in the electronic structure of CoII centers through remote ligand substitution can significantly affect the NMR and CEST properties of Co2-based PARACEST probes. Variable-pH NMR and CEST analyses reveal that the chemical shifts of the ligand protons
我们报告了三个新的基于Co 2的顺磁化学交换饱和转移(PARACEST)探针,能够按比例定量pH值。Co II 2络合物[LCo 2(etidronate )] -,具有四(羧酰胺)和OH取代的依替膦酸酯配体,具有相反的pH依赖性CEST峰强度,先前已显示出log(CEST OH / CEST)之间呈线性相关NH)和pH在6.5-7.6范围内,在37°C时灵敏度为0.99(7)pH单位–1。在这里,我们通过一系列CF 3官能化的Co II 2配合物[(X L')Co2(etidronate)] -(X = NO 2,F,Me),通过远距离配体取代而引起的Co II中心电子结构的适度变化会显着影响基于Co 2的PARACEST探针的NMR和CEST特性。可变pH NMR和CEST分析表明,配体质子的化学位移受X取代基的性质高度影响。对于X = NO 2,F和Me,分别在115和88、93和79以及88和76
Effect of Ligand Structure on the Zinc-Catalyzed Henry Reaction. Asymmetric Syntheses of (−)-Denopamine and (−)-Arbutamine
作者:Barry M. Trost、Vince S. C. Yeh、Hisanako Ito、Nadine Bremeyer
DOI:10.1021/ol020077n
日期:2002.8.1
[reaction: see text] Syntheses of variously modified ligands for the dinuclear zinc catalysts for the asymmetric aldol and nitroaldol (Henry) reactions are reported. Catalytic enantioselective nitroaldol reactions promoted by these modified ligands led to efficient syntheses of the beta-receptor agonists (-)-denopamine and (-)-arbutamine.
Reaction of o-xylenyl dibromide with dipotassium salt of 2-nitro-1,1-ethanedithiol afforded nitroethylenophane 2. Similar strategy has been used for the synthesis of cyclophanes 7, 9 and 11.