Catalytic, Enantioselective Aldol Additions to Ketones
作者:Scott E. Denmark、Yu Fan
DOI:10.1021/ja025670e
日期:2002.4.1
(possessing both axial and central chiral elements) the aldol addition takes place again in excellent yield and with good stereoselectivity. The enantioselectivities of the additions are highly variable (7-86% ee) and are strongly dependent on the structure of the ketone acceptor. Aromatic methylketones gave the highest selectivity, whereas olefinic ketones were the least selective.
已经证明了三氯甲硅烷基乙烯酮缩醛对酮的催化、对映选择性加成。在催化量的吡啶 N-氧化物存在下,乙酸甲酯的三氯甲硅烷基烯醇化物与多种酮(芳香族、烯烃、炔属、脂肪族)发生快速和高产率的羟醛加成反应。此外,在催化量(10 mol%)的手性双吡啶双 N 氧化物(具有轴性和中心手性元素)存在下,醛醇加成再次以优异的产率和良好的立体选择性发生。添加物的对映选择性变化很大(7-86% ee)并且强烈依赖于酮受体的结构。芳族甲基酮的选择性最高,而烯酮的选择性最低。
Chiral bipyridine–copper(II) complex. Crystal structure and catalytic activity in asymmetric cyclopropanation
作者:Hoi-Lun Kwong、Wing-Sze Lee、Hung-Foon Ng、Wing-Hong Chiu、Wing-Tak Wong
DOI:10.1039/a706754b
日期:——
A chiral bipyridineâcopper(II) complex has been prepared and its crystal structure determined. The structure involves a CuN2Cl2 compressed tetrahedral stereochemistry. Chiral bipyridine complexes of copper-(I) and -(II) triflate are active catalysts for asymmetric cyclopropanation of alkenes with enantiomeric excesses up to 92%.
The scandium-bipyridine-catalyzedenantioselective addition of anilines and O-alkyl hydroxylamines to meso-epoxides has been optimized and extended to a broad range of epoxides and amines. Whereas aromatic meso-epoxides generally furnished the corresponding 1,2-amino alcohols in excellent enantioselectivities, aliphatic meso-epoxides only gave rise to moderate enantioselectivities in the aminolysis
Chiral zinc(II) bipyridine complex. Crystal structure and catalytic activity in asymmetric allylation reaction
作者:Hoi-Lun Kwong、Kwok-Mei Lau、Wing-Sze Lee、Wing-Tak Wong
DOI:10.1039/a902177i
日期:——
A chiral bipyridine zinc(II) complex, Zn(L)Cl2 (L=chiral bipyridine), has been prepared and characterized by usual spectroscopic means and X-ray crystallography. Reaction of Zn(L)Cl2 with AgCF3SO3 gave Zn(L)(CF3SO3)2insitu; this complex is an active catalyst for allylation of aldehydes with enantiomeric excesses up to 60%.
已经制备了手性联吡啶锌(II)配合物Zn(L)Cl 2(L =手性联吡啶),并通过常规的光谱学方法和X射线晶体学对其进行了表征。锌(的反应大号)氯2在AgCF 3 SO 3,得到的Zn(大号)(CF 3 SO 3)2在原位; 该络合物是一种活性催化剂,可用于醛基烯丙基化,对映体过量不超过60%。
Zinc complex of bipyridine crown macrocycle: Luminescence sensing of anions in aqueous media via the cooperative action of metal-ligand and hydrophobic interactions
Abstract A metallomacrocyclic receptor ( 1 ) based on a Zn(II) · bipyridine complex and a crown ether has been developed for luminescence sensing of anions; receptor 1 coordinates anions via the cooperative action of metal-ligand and hydrophobic interactions in aqueous media with strong fluorescence enhancement for RCOO − .