Planarchiral 5,11‐disubstiuted dibenzo[a,e]cyclo‐octatetraenes (dbCOTs) have been developed as the first useful chiral homologs to dbCOT‐ligands for asymmetric applications. Methods enabling the preparation of such compounds on a gram‐scale in enantiomerically pure form are described. Evaluated as ligands in rhodium(I)‐catalyzed 1,4‐ and 1,2‐arylation reactions, tertiary and quarternary stereogenic
Synthesis of Dibenzo[a,e]cyclooctene-5,11(6H,12H)-diones via the Elusive Benzocyclobutenone Anion
作者:Yu Liu、Ping Lu、Yingchao Huang、Jun Chen
DOI:10.1055/a-1545-7706
日期:2021.12
We reported here a facile synthesis of dibenzo[a,e]cyclooctene-5,11(6H,12H)-diones via dimerization of benzocyclobutenones in the presence of simple base via the elusive benzocyclobutenone anion. The temperature effect played a crucial role in the dimerization reaction. Further synthesis of 5,11-disubstituted dibenzo[a,e]cyclooctenes (dibenzo[a,e][8]annulenes) from dibenzo[a,e]cyclooctene-5,11(6H
Benzocyclobutenone enolate: an anion with an antiaromatic resonance structure †
作者:Katherine M. Broadus、Steven R. Kass
DOI:10.1039/a905868k
日期:——
Benzocyclobutenone enolate (1a) was synthesized by deprotonating its conjugate acid with fluoride ion in the gas phase using a Fourier transform mass spectrometer. Reactions of 1a were explored and C-alkylation was found to be greatly preferred over oxygen attack. Thermodynamic properties (ÎH°acid(1) = 360.3 ± 2.1 kcal molâ1, EA(benzocyclobutenyl radical) = 1.90 ± 0.10 eV, and BDE(CâH) = 90.5 ± 3.1 kcal molâ1) also were measured. The results are contrasted to ab initio calculations on cyclobutanone, benzocyclobutenone, and cyclobutenone enolates. Natural bond orbital and Bader analyses are reported too. Given our gas phase and computational results, we were able to devise conditions for the generation and trapping of 1a in tetrahydrofuran despite previous failings reported in the literature.
利用傅立叶变换质谱仪,通过在气相中用氟离子对其共轭酸进行去质子化,合成了苯并环丁烯酮烯醇盐(1a)。研究人员对 1a 的反应进行了探讨,发现 C-烷基化反应比氧攻击反应更受青睐。此外,还测量了热力学性质(δH°acid(1) = 360.3 ±Â 2.1 kcal molâ1、EA(苯并环丁烯基) = 1.90 ±Â 0.10 eV 和 BDE(CâH) = 90.5 ±Â 3.1 kcal molâ1)。这些结果与环丁酮、苯并环丁烯酮和环丁烯酮烯醇化合物的 ab initio 计算结果进行了对比。此外,还报告了自然键轨道和 Bader 分析。鉴于我们的气相和计算结果,我们能够设计出在四氢呋喃中生成和捕获 1a 的条件,尽管之前有文献报道过失败的情况。
Copper(I) Catalyzed Decarboxylative Synthesis of Diareno[<i>a</i>,<i>e</i>]cyclooctatetraenes
Diareno[a,e]cyclooctatetraenes find widespread applications as building blocks, ligands, and responsive cores in topologically switchable materials. However, current synthetic methods to these structures suffer from low yields or operational disadvantages. Here, we describe a practical three-step approach to diareno[a,e]cyclooctatetraenes using an efficient copper(I) catalyzed double decarboxylation
二芳基[ a , e ]环辛四烯在拓扑可切换材料中作为构件、配体和响应核具有广泛的应用。然而,目前这些结构的合成方法存在产率低或操作上的缺点。在这里,我们描述了一种实用的三步法制备二芳基 [ a , e ] 环辛四烯,使用高效的铜 (I) 催化双脱羧作为关键步骤。该序列依赖于廉价和丰富的试剂,很容易大规模进行,并且还适用于扩展这类有趣结构的效用的不对称衍生物。
Cyclic Polyolefins. XIV. 3,7-Dibromo-1,2,5,6-Dibenzcycloöctadiene and 1,2,5,6-Dibenzcycloöctatetraene