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 aldol products with variable enantioselectivities
描述了等同于酮的乙酸烯醇酯的催化对映选择性加成。在吡啶N-氧化物的存在下,甲基三氯甲硅烷基烯酮缩醛与多种酮反应,以优异的产率提供醛醇加成产物。在3,3'-和6,6'-位置带有各种取代基的手性2,2'-吡啶基双-N-氧化物还提供优异的醛醇产物收率,其对映体选择性的变化范围从芳香族酮的94/6 er到对于脂肪族酮几乎是外消旋的。催化剂与四氯化硅(((P)-(R,R)-19· SiCl 4))已获得。大量的计算分析为观察到的对映选择性趋势提供了立体化学原理。