Structurally Simple Pyridine <i>N</i>-Oxides as Efficient Organocatalysts for the Enantioselective Allylation of Aromatic Aldehydes
作者:Luca Pignataro、Maurizio Benaglia、Rita Annunziata、Mauro Cinquini、Franco Cozzi
DOI:10.1021/jo052132m
日期:2006.2.1
A series of structurally simple pyridine N-oxides have readily been assembled from inexpensive amino acids and tested as organocatalysts in the allylation of aldehydes with allyl(trichloro)silane to afford homoallylic alcohols. (S)-Proline-based catalysts afforded the products derived from aromatic aldehydes in fair to good yields and in up to 84% enantiomeric excess (ee). The allylation of heteroaromatic
一系列结构简单的吡啶N-氧化物已经很容易地由廉价的氨基酸组装而成,并且在醛与烯丙基(三氯)硅烷的烯丙基化反应中作为有机催化剂进行了测试,得到了均烯丙基醇。(S脯氨酸为基础的催化剂提供了从芳族醛衍生的产物,其收率中等至良好,对映体过量(ee)高达84%。杂芳族,不饱和和脂族醛的烯丙基化不太令人满意。通过在非手性和手性添加剂以及结构上不同的催化剂存在下进行反应,我们收集了有关立体化学结果与催化剂结构特征之间关系的一些见解。即使所获得的ee值不如其他催化剂所观察到的最佳值,这项工作也表明,结构简单的吡啶N-氧化物还可以促进烯丙基化反应,并具有令人满意的立体控制。