Aldol reactions of 2-thioxotetrahydropyrimidin-4(1H)-ones: stereoregulations from endo- and exocyclic chiral centres
作者:Varun Kumar、Kapil Kumar、Anang Pal、Gopal Lal Khatik、Vipin A. Nair
DOI:10.1016/j.tet.2012.12.020
日期:2013.2
reactions of conformationally restricted 3-aryl-1-((S)-1-phenylethyl)-2-thioxotetrahydropyrimidin-4(1H)-ones governed the formation of anti aldol adducts, by a kinetic reaction pathway. The preferential formation of the anti aldol diastereomers was also assisted by the steric effects of the electrophile through diastereofacial selection while the electronic effects of the aryl group at N3 remained subtle.
在锂介导的构象受限的3-芳基-1-(-1-((S)-1-苯乙基)-2-硫代四氢嘧啶-4(1 H)-的不对称醛醇缩合反应中,N 1处的取代基所赋予的空间规则决定了吗啉的形成。抗醛醇加合物,通过动力学反应途径。通过非对映体选择,亲电子体的空间效应也有助于抗醛醇非对映异构体的优先形成,而在N 3上的芳基的电子效应仍然微不足道。在C6处结合一个内环甲基见证了一个非对映体选择性的形成一个抗通过调节π-表面选择性使醛醇加成物。醛醇加合物的绝对构型通过计算计算和NMR实验确定,并通过单晶X射线分析证实。