A Chiral Axis due to an Acyclic Imide–Ar Bond: a Study of Steric Effects of Acyl Groups on Racemization
作者:Kazuhiro Kondo、Takeko Iida、Hiroko Fujita、Tomoko Suzuki、Kentaro Yamaguchi、Yasuoki Murakami
DOI:10.1016/s0040-4020(00)00852-8
日期:2000.11
small one racemized more easily. To explain this observed phenomenon, 13C NMR experiments and the reaction with benzylamine of 3a–e were undertaken. These results suggested that the t-BuCO–N bond in 3a which racemized easily, is more twisted, compared with the RCO–N bonds in 3b–e which are relatively stable to racemization. Furthermore, the absolute configuration of 3b and 3c has been determined to be
描述了对一系列旋光化合物3a – e的外消旋作用的研究,包括其酰基的空间效应。光学活性化合物3c和3d的第一个例子,据报道具有基于无环酰亚胺-Ar键的轴向手性。已经揭示了非常有趣的结果,即带有大体积酰基而不是相对小的酰基的3a更容易外消旋。为了解释这种现象,我们进行了13 C NMR实验以及与3a - e的苄胺反应。这些结果表明3a中的t -BuCO–N键与3b - e中的RCO-N键相对于外消旋化相对稳定相比,容易外消旋的扭转性更大。此外,通过CD光谱已经确定了3b和3c的绝对构型为R,并且已经完成了外消旋体3f的X射线晶体学分析。