Synthesis and stereoisomerism of [n]cyclo-2,9-phenanthrenylene congeners possessing alternating E/Z- and R/S-biaryl linkages
Synthesis and stereoisomerism of [n]cyclo-2,9-phenanthrenylene congeners possessing alternating E/Z- and R/S-biaryl linkages
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具有交替E/Z-和R/S-联芳基键的[n]环-2,9-亚菲同系物的合成和立体异构
DOI：
10.1039/d0ob01064b
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发表时间：
2020
影响因子：
3.2
通讯作者：
Sato Sota
中科院分区：
文献类型：
--
作者：
Yang Yong;Nanjo Yuki;Isobe Hiroyuki;Sato Sota
详细阐述了具有E/Z-和R/S-杂联芳基键的[n]环-2，9-菲烯（[n] CPhen 2，9，n = 4，6和8）的合成和环立体异构。使用菲衍生物的二聚体作为起始材料，并进行Ni介导的Yamamoto型偶联，得到[6] CPhen 2，9作为主要环状产物，以及[4] CPhen 2，9和[8] CPhen 2，9作为次要产物。[n] CPhen 2，9的立体异构体被分离和表征，并且立体异构体的数量表明E/Z键不提供任何实验上可分离的异构体，而[n] CPhen 2，9中的手性源自受限R/S键处的固有轴向手性。理论计算表明，[n] CPhen 2，9中的2，2 ′-键采用固定的Z-或E-构型，这表明与已报道的刚性或柔性行为相反，存在一种新型的阻转异构动力学。本研究丰富了我们对芳香大环中E/Z键的立体化学特征的理解。
The synthesis and cyclostereoisomerism of [n]cyclo-2,9-phenanthrenylenes ([n]CPhen2,9, n = 4, 6 and 8), possessing hybrid E/Z- and R/S-biaryl linkages, were elaborated. The dimer of a phenanthrene derivative was used as a starting material and underwent Ni-mediated Yamamoto-type coupling to afford [6]CPhen2,9 as a major cyclic product, as well as [4]CPhen2,9 and [8]CPhen2,9 as minor products. The stereoisomers of [n]CPhen2,9 were isolated and characterized, and the number of stereoisomers indicated that E/Z linkages did not provide any experimentally separable isomers, whereas the chirality in [n]CPhen2,9 originated from the intrinsic axial chirality at constrained R/S linkages. Theoretical calculations predicted that the 2,2′-linkages in [n]CPhen2,9 adopted a fixed Z- or E-configuration, which suggested a novel type of dynamics of atropisomerism in contrast to the reported rigid or flexible behavior. This study enriches our understanding of the stereochemical features of E/Z linkages in aromatic macrocycles.