Li Liu, Long Stephen M, Selvaraj Nathaniel J, Dolinar Brian S, Popp Brian V, Wang Kung K
C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States.
Org Lett. 2025 Jun 27;27(25):6578-6582. doi: 10.1021/acs.orglett.5c01384. Epub 2025 Jun 17.
Carbon nanohoops are an emerging class of cyclic conjugated molecules that have drawn significant attention for their unique optoelectronic properties and potential applications in nanomaterials. We report herein the synthesis of two novel carbon nanohoops with structures as [9]cycloparaphenylene ([9]CPP) derivatives having three picene units with each substituted by two carbomethoxy groups. A substrate bearing a hexahydropicene unit with the two bromophenyl groups to each other through the Diels-Alder reaction with dimethyl acetylenedicarboxylae was prepared in four steps from 6-bromo-1-tetralone. A subsequent Ni(cod)/bpy-mediated macrocyclization reaction followed by a DDQ-promoted oxidation step of the central six-membered ring and the dimethylene linkages produced a pair of cyclic - and -trimers because of the slow rotation of the dicarbomethoxy-substituted picene units. This work not only introduces new CPP architecture but also provides insights into the potential extension of this methodology toward the synthesis of cyclophenacenes as carbon nanobelts.
碳纳米环是一类新兴的环状共轭分子，因其独特的光电特性以及在纳米材料中的潜在应用而备受关注。本文报道了两种新型碳纳米环的合成，其结构为[9]环对亚苯基（[9]CPP）衍生物，含有三个并五苯单元，每个单元被两个甲氧基羰基取代。通过狄尔斯-阿尔德反应，由6-溴-1-萘满酮经四步反应制备出一种带有六氢并五苯单元且两个溴苯基彼此相连的底物。随后，在镍（零价）/联吡啶介导的大环化反应之后，通过2,3-二氯-5,6-二氰基对苯醌（DDQ）促进的中心六元环和二亚甲基键的氧化步骤，由于二甲氧基羰基取代的并五苯单元旋转缓慢，生成了一对环状三聚体和三聚体。这项工作不仅引入了新的CPP结构，还为将该方法潜在扩展用于合成作为碳纳米带的环菲提供了思路。
