C. Eugene Bennett Department of Chemistry, West Virginia University , Morgantown, West Virginia 26506-6045, United States.
J Org Chem. 2017 Jan 20;82(2):1166-1174. doi: 10.1021/acs.joc.6b02789. Epub 2017 Jan 9.
The Diels-Alder reactions between 2 equiv of (E,E)-1,4-bis(4-bromophenyl)-1,3-butadiene and 1,4-benzoquinone led to the formation of a key intermediate with all four 4-bromophenyl substituents cis to one another. The subsequent nickel-mediated homocoupling reactions then produced partially hydrogenated cycloparaphenylenes, including a molecule bearing two units of tetrahydro[6]cycloparaphenylene (4H[6]CPP) fused together through two 1,4-dimethoxybenzene units in an armchair (6,6)carbon nanotube-like connection. Similarly, two 6H[9]CPPs were connected through three 1,4-dimethoxybenzene units in an armchair (9,9)carbon nanotube-like arrangement. A bent 8H[12]CPP and a bent 12H[18]CPP, which were fused intramolecularly with two and three 1,4-dimethoxybenzene units, respectively, to create the bent structures, were likewise synthesized. A molecule containing a bent 8H[12]CPP fused to a 4H[6]CPP was likewise constructed. The structures of these partially hydrogenated CPPs were established by X-ray structure analysis, NMR spectroscopy, and additional independent synthetic pathways.
(E,E)-1,4-双(4-溴苯基)-1,3-丁二烯与 1,4-苯醌之间的 Diels-Alder 反应导致形成了一个关键的中间体，其中四个 4-溴苯基取代基彼此处于顺式构型。随后的镍介导的同偶联反应产生了部分氢化的环并对苯撑，包括一个分子，其两个四氢[6]环并对苯撑（4H[6]CPP）单元通过两个 1,4-二甲氧基苯单元在扶手椅（6,6）碳纳米管状连接中融合在一起。同样，两个 6H[9]CPP 通过三个 1,4-二甲氧基苯单元在扶手椅（9,9）碳纳米管状排列中连接。一个弯曲的 8H[12]CPP 和一个弯曲的 12H[18]CPP，它们分别通过两个和三个 1,4-二甲氧基苯单元融合形成了弯曲结构，也被合成了。一个包含弯曲的 8H[12]CPP 与 4H[6]CPP 融合的分子也被构建了。这些部分氢化 CPP 的结构通过 X 射线结构分析、NMR 光谱和其他独立的合成途径确定。
