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。
(<i>o</i>-Hydroxyphenyl)methylphosphonic acids: Synthesis and potentiometric determinations of their p<i>K</i><sub>a</sub>Values
(o-Hydroxyphenyl)methylphosphonic acids are readily obtained from o-(bromomethyl)- or o-(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pKavalues have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric
从邻-(溴甲基)-或邻-(羟甲基)酚和亚磷酸三烷基酯容易获得(邻-羟基苯基)甲基膦酸。随后的水解产生相应的膦酸。对于一系列此类化合物,p K a值已通过电位计确定。根据电子和空间效应,讨论了它们对芳环中其他取代基的依赖性。
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.
Coupling of Carbon Dioxide with Epoxides Efficiently Catalyzed by Thioether-Triphenolate Bimetallic Iron(III) Complexes: Catalyst Structure-Reactivity Relationship and Mechanistic DFT Study
作者:Francesco Della Monica、Sai V. C. Vummaleti、Antonio Buonerba、Assunta De Nisi、Magda Monari、Stefano Milione、Alfonso Grassi、Luigi Cavallo、Carmine Capacchione
DOI:10.1002/adsc.201600621
日期:2016.10.20
highly Lewis acidic catalysts. In combination with tetrabutylammonium bromide (TBAB) they are highly active catalysts in the synthesis of cyclic organic carbonates through the coupling of carbondioxide to epoxides with the highest initial turnover frequencies reported to date for the conversion of propylene oxide to propylene carbonate for iron‐based catalysts (5200 h−1; 120 °C, 2 MPa, 1 h). In particular
制备了一系列由硫醚-三酚盐配体支撑的双核铁(III)I配合物,以获得高度路易斯酸性的催化剂。与四丁基溴化铵(TBAB)结合使用时,它们是环状有机碳酸酯合成中的高活性催化剂,通过二氧化碳与环氧化物的偶联反应,迄今为止报道的最高周转频率是铁基环氧丙烷转化为碳酸丙烯酯的最高转换频率催化剂(5200 h -1; 120°C,2 MPa,1 h)。特别地,这些络合物显示出是用于将二氧化碳偶联至内部环氧乙烷的高度选择性的催化剂,其以良好的产率提供了相应的环状碳酸酯并且保留了初始立体化学构型。密度泛函理论(DFT)研究为这些Fe(III)配合物的相对较高的活性提供了一个合理的理由,显示了配体骨架中半不稳定的硫原子在促进反应性方面的基本作用。值得注意的是,尽管催化剂前体具有双核性质,但在催化循环中仅涉及一个金属中心。
Synthesis of Macrocyclic Cage Compounds by Diamine−Dihalide One-Step Coupling Reaction
Macropolycycliccagecompounds were synthesized by a direct reaction between diamines and bis(bromomethyl) compounds. The procedure for constructing the polycyclic cage structure is simple and straightforward. The macropolycycliccompounds obtainable from this cyclization procedure are three-dimensional cagecompounds, and any other isomers were not obtained except for two examples. Benzene, pyridine