Asymmetric reduction of prochiral cycloalkenones. The influence of exocyclic alkene geometry
作者:Alison F. Simpson、Corinna D. Bodkin、Craig P. Butts、Mark A. Armitage、Timothy Gallagher
DOI:10.1039/b004540n
日期:——
The asymmetric reduction of a series of prochiral enones of general structure 1 using the Corey oxazaborolidine 2, leading to enantiomerically enriched allylic cycloalkanols 3 is described. The influence of alkene geometry on both the sense (Rvs. S) and efficiency (% ee) of the asymmetric reduction process has been probed for two systems, (E)- and (Z)-4 and (E)- and (Z)-7, based on cyclohexanone and cyclopentanone respectively. The absolute stereochemistry of the cyclopentyl derivative (E)-8 has been established by X-ray crystallographic analysis of carbamate 10. The ability to assign an absolute configuration to allylic alcohols 3, based on the NMR methods described earlier by Riguera, has been evaluated.
本研究介绍了使用科里噁唑硼烷 2 对一系列具有一般结构 1 的手性烯酮进行不对称还原,从而得到对映体富集的烯丙基环烷醇 3 的过程。在分别基于环己酮和环戊酮的 (E)- 和 (Z)-4 和 (E)- 和 (Z)-7 两个系统中,探究了烯烃几何形状对不对称还原过程的意义 (Rvs. S) 和效率 (% ee) 的影响。通过对氨基甲酸酯 10 进行 X 射线晶体分析,确定了环戊基衍生物 (E)-8 的绝对立体化学结构。根据 Riguera 早先描述的核磁共振方法,对分配烯丙基醇 3 绝对构型的能力进行了评估。