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。
Electroreductive coupling of methallylchloride or methyl chloroacetate with carbonyl compounds catalyzed by nickel bipyridine complexes
β-hydroxy esters in the presence of catalytic amounts of the NiBr2(2,2′-bipyridine) complex has been developped from mixed electrolysis of methallylchloride, or methylchloroacetate with several carbonylcompounds, using a one-compartment cell equiped of a sacrificial zinc anode.
THE DEHYDRATION OF 3-HYDROXY-3,4,4-TRIMETHYLPENTANOIC ACID<sup>1</sup>
作者:MELVIN S. NEWMAN、RONALD ROSHER
DOI:10.1021/jo01185a003
日期:1944.5
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