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。