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。
The synthesis of presumably planar conjugated 8-membered ring compounds
作者:Tze-Lock Chan、Nai Zheng Huang、Franz Sondheimer
DOI:10.1016/s0040-4020(01)88542-2
日期:1983.1
Using mainly base dehydrobromination reactions of carbocyclic 8-membered bromides, a variety of acetylenic and cumulenic compounds were isolated or postulated as transient intermediates. The physical and chemical properties of the isolable presumably planar 8-memberedring compounds were investigated. Trapping experiments were used to confirm the transitory existence of the unstable intermediates.
Treatment of cyclobutanone having an o-styryl group at the 2-position with a catalytic amount of rhodium–phosphine complex afforded eight-membered ring ketones via intramolecular insertion of the C...
用催化量的铑-膦配合物处理2-位具有邻苯乙烯基的环丁酮,通过C的分子内插入得到八元环酮...
Oxidative rearrangement of 1,1-disubstituted alkenes to ketones
作者:Qiang Feng、Qian Wang、Jieping Zhu
DOI:10.1126/science.adg3182
日期:2023.3.31
to the ring expansion of highly strained methylene cyclobutane derivatives. Herein, we report a solution to this synthetic challenge by designing a Pd II /Pd IV catalytic cycle incorporating a 1,2-alkyl/Pd IV dyotropic rearrangement as a key step. This reaction, compatible with a broad range of functional groups, is applicable to both linear olefins and methylenecycloalkanes, including macrocycles.