Absolute configurations and CD spectra of axially chiral biphenyls prepared in a facile manner by crystallization-induced configuration transformation
作者:Limin Wang、Senxiang Cheng、Rongfeng Chen、Junbiao Chang
DOI:10.1002/chir.20828
日期:——
the biphenyls was thus achieved. It was found that amide formation of an (S)‐valinol or (S)‐phenylalaninol at the 2′‐position of the biphenyl usually induced the deposition of crystals with the (M)‐configuration from ethanol in yields higher than 50%. The absolute configurations (ACs) of two crystalline biphenyls have been determined by X‐ray crystallographic analysis. The ACs of nine biphenyls have been
轴向手性联苯如(M,S)‐ 3k可通过将其非对映异构体混合物结晶而方便地获得,它们是由外消旋4,4'-二甲氧基-5,6,5',6'-双(亚甲基二氧基)-合成的2-羧酸酯基-2'-羧基联苯4个手性氨基醇([R)-alaninol,(小号)-alaninol,(小号) -缬氨醇,和(小号) -苯丙氨醇。由此实现了联苯的结晶诱导构型转变。发现(S)-缬氨醇或(S的酰胺形成)联苯2'-位处的苯丙氨醇通常会诱导乙醇中具有(M)构型的晶体沉积,产率高于50%。X射线晶体学分析确定了两个结晶联苯的绝对构型(AC)。九个联苯的AC已根据其CD光谱进行分配。此外,对这些轴向手性联苯的稳定性研究表明,AC可以在重新溶解后还原。能量势垒,以(差向异构化之间P,- [R )-图3b和(中号,- [R )- 3b中被测量为Δ G ^ #= 21.45 kcal / mol,在301 K下的乙醇半衰期为17.1 h。手性,2010年。©2010