Lewis Base Catalyzed, Enantioselective Aldol Addition of Methyl Trichlorosilyl Ketene Acetal to Ketones
作者:Scott E. Denmark、Yu Fan、Martin D. Eastgate
DOI:10.1021/jo0506276
日期:2005.6.1
addition of an acetate enolate equivalent to ketones is described. Methyl trichlorosilyl ketene acetal reacts with a wide range of ketones in the presence of pyridine N-oxide to afford the aldol addition products in excellent yields. Chiral 2,2‘-pyridyl bis-N-oxides bearing various substituents at the 3,3‘- and 6,6‘-positions also provide excellent yields of the aldolproducts with variable enantioselectivities
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。
Catalytic Enantioselective Aldol Reaction to Ketones
An enantioselective aldol reaction between ketones and ketene silyl acetals is described using CuF-chiral phosphine as a catalyst. The key for high enantioselectivity was the development of a novel ligand derived from Taniaphos combined with the unique accelerative effect of PhBF3K. These conditions are applicable to various substrates such as aromatic, aliphatic, and heteroaromatic ketones. In the
AbstractTwo methods for the synthesis of newaxiallychiral bipyridine N,N′-dioxides based on catalytic [2+2+2] cyclotrimerization of diynes with nitriles were developed. The N,N′-dioxides were used as catalysts in enantioselectiveallylation of benzaldehyde with allyltrichlorosilane and aldol reaction of trichlorosilyl ketene acetal of methyl acetate with acetophenone. Graphical abstract
Theoretical modelling of pyrolysis reactions. Thermal retroaldol reactions of β-hydroxyesters
作者:Yoram Houminer、James Kao、Jeffrey I. Seeman
DOI:10.1039/c39840001608
日期:——
Reaction rate constants for the thermalretroaldolreaction of eight β-hydroxyesters were determined, and these were well correlated with MM2-derived steric energies.