Conformation of Eight-Membered Benzoannulated Lactams by Combined NMR and DFT Studies
作者:Agnieszka Witosińska、Bogdan Musielak、Paweł Serda、Maria Owińska、Barbara Rys
DOI:10.1021/jo301859h
日期:2012.11.2
were synthesized, and their structure and conformational behavior in solution (NMR and DFT), in the gas phase (DFT), and, for some of them, in the solid state (X-ray) were investigated. The variable-temperature NMR spectra were employed to determine the conformational equilibria and the activation energy of the conformational changes of the eight-membered ring. The coalescence effects are assigned to
合成了标题化合物,并研究了它们在溶液中(NMR和DFT),在气相(DFT)中以及对于其中一些在固态(X射线)中的结构和构象行为。使用可变温度NMR光谱确定八元环的构象平衡和构象变化的活化能。聚结效应被分配给手性基态构象的外消旋化,该手性基态构象在38–100 kJ mol –1的范围内具有环反转势垒,这取决于两个强构象约束条件的相对设置:苯并环化和酰胺功能。第二个构象过程,即苯并[ c ]偶氮素-3-one,苯并[观察到d ]偶氮星-2-酮和苯并[ d ]偶氮星-4-酮。通过分析实验数据和计算得出的NMR数据,阐明了溶液中观察到的构象异构体的性质。结合先前关于(Z,Z)-环辛二烯及其苯并类似物的实验和理论数据讨论了目前的结果。