Synthesis of Contorted Polycyclic Conjugated Hydrocarbons via Regioselective Activation of Cyclobutadienoids
Synthesis of Contorted Polycyclic Conjugated Hydrocarbons via Regioselective Activation of Cyclobutadienoids
复制标题
通过环丁二烯类化合物的区域选择性活化合成扭曲多环共轭烃
DOI：
10.1021/jacs.2c02457
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发表时间：
2022
影响因子：
15
通讯作者：
Xia, Yan
中科院分区：
文献类型：
--
作者：
Yin, Xianglin;Zheng, Ke;Jin, Zexin;Horst, Matias;Xia, Yan
在过去的十年中，扭曲碳结构因其丰富的三维几何形状、增强的溶解度和可调谐的电子性质而引起了广泛的关注。我们报告了一种模块化的方法来合成在控制拓扑结构中含有螺旋部分的扭曲多环共轭烃。这一策略利用了我们之前报道的流线型合成含有四元环丁二烯（CBDs）的π-体系，其催化环加成与炔提供螺旋结构。有趣的是，我们观察到在我们的系统中，CBDs的C-C键激活具有独特的非海湾区域选择性，这与之前很少的[N]苯激活导致线性苯结构形成的例子相反。非海湾区炔环加成的定量和区域选择性生成了多种螺旋碳结构，其拓扑结构由含cbd的前体烃决定。四元环的外环甲基取代基可以抑制环加成，从而允许只选择性激活某些所需的CBD单元，而保持其他单元完整。计算阐明了观察到的区域选择性的基础。所描述的方法提供了一条新的途径，以多螺旋芳烃具有复杂的尚未定义的几何结构，促进了进一步探索这些迷人的碳结构。
Contorted carbon structures have drawn much attention in the past decade for their rich three-dimensional geometries, enhanced solubility, and tunable electronic properties. We report a modular method to synthesize contorted polycyclic conjugated hydrocarbons containing helical moieties in controlled topologies. This strategy leverages our previously reported streamlined synthesis of π-systems containing four-membered cyclobutadienoids (CBDs), whose catalyzed cycloaddition with alkynes affords helical structures. Interestingly, we observed exclusive nonbay region regioselectivity in the C–C bond activation of CBDs in our system, which is opposite to the scarce previous examples of [N]phenylene activation that led to the formation of linear phenacene structures. The quantitative and regioselective nonbay region alkyne cycloaddition yielded a variety of helical carbon structures with their topologies predetermined by the CBD-containing precursor hydrocarbons. The cycloaddition can be inhibited by methyl substituents exocyclic to the four-membered ring, thus allowing selective activation of only certain desired CBD units while leaving the others intact. Calculation elucidated the basis for the observed regioselectivity. The described method provides a new route to multihelical aromatic hydrocarbons with complex yet defined geometries, facilitating the further exploration of such fascinating carbon structures.