Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine substitution (S-(−)-(E)-1). A reductive debromination of S-(−)-(E)-1 results in formation of one of the enantiomers of (E)-2. Using a combination of HPLC and CD spectroscopy we could safely assign the stereostructure of one of the enantiomers of (E)-2, the reduced product R-(−)-(E)-1.
单晶X射线衍射是确定手性分子绝对立体结构的常用方法之一。然而,该方法仅适用于含有重原子的分子或具有重元素或手性内部参考的分子。本文报告了使用一种反向方法,即使用已知立体结构的前体物(
溴代物S-(-)-(E)-1)的脱功能化来确定分子(E)-2的对映体的绝对立体结构。S-(-)-(E)-1的还原去
溴反应会生成(E)-2的其中一种对映体。使用高效
液相色谱和圆二色光谱的组合,我们可以安全地确定(E)-2的其中一种对映体的立体结构,即还原产物R-(-)-(E)-1。