Generation of All-Carbon Quaternary Stereocenters at the C-3 Carbon of Lactams via [3,3]-Sigmatropic Rearrangement and Revision of Absolute Configuration: Total Synthesis of (−)-Physostigmine
作者:Ganesh Pandey、Jagadish Khamrai、Akash Mishra
DOI:10.1021/acs.orglett.7b03537
日期:2018.1.5
via Johnson–Claisen rearrangement of γ-hydroxy-α,β-unsaturated lactams. It has been observed that olefin geometry plays an important role in the development of the absolute stereochemistry of the product. Dependence of product configuration on the olefin geometry is explained by postulating probable transition states. The success of this method has been shown for multigram-scale synthesis of these substituted
通过γ-羟基-α,β-不饱和内酰胺的Johnson-Claisen重排,已经开发了到环状内酰胺C-3位置上所有碳四级立体中心的非对映选择性途径(最高> 99%)。已经观察到烯烃的几何形状在产物的绝对立体化学的发展中起重要作用。通过假设可能的过渡态来解释产物构型对烯烃几何形状的依赖性。从可商购的廉价起始原料成功地以克级合成这些取代的内酰胺,表明了该方法的成功。通过进行(-)-毒扁豆碱的全合成也证明了该方法的合成有用性。