Chiral Homoenolate Equivalents, V. Hydroxylakylation of Lithiated 3‐[(
<i>S</i>
)‐2‐(Methoxymethyl)pyrrolidino]‐1,3‐diphenylpropene – An Asymmetric Homoaldol Reaction
作者:Hubertus Ahlbrecht、Andreas Kramer
DOI:10.1002/cber.19961291004
日期:1996.10
hydroxyalkylation of lithiated 3-[(S)-2-(methoxymethyl)-pyrrolidino]-1,3-diphenylpropene (2) with aldehydes is completely regioselective giving homoaldol adducts in good yields. The simple diastereoselectivity is low with typical ratios ranging between 1:1 and 1:3 with the syn isomer predominating. The induced diastereoselectivity is much higher and is strongly solvent-dependent. The reaction predominantly
锂化的3-[((S)-2-(甲氧基甲基)-吡咯烷基] -1,3-二苯基丙烯(2)的羟烷基与醛的完全区域选择性,以高收率得到均醛醇加合物。简单的非对映选择性是低的典型比率1之间的范围内:1和1:3顺式异构体为主的。诱导的非对映选择性更高,并且强烈依赖溶剂。该反应主要根据金属固位机理在THF以及TBME中从烯丙基系统的si侧进行。通过使用较少溶剂化的TBME所获得的诱导的非对映选择性大大高于在强溶剂化THF中的诱导的非对映选择性,达到了高达97%ee的选择性。